LWN.net Weekly Edition for October 16, 2003

LinkSys and binary modules

In response to pressure from the Free Software Foundation and the community, LinkSys has made a new tarball available containing the source for the firmware running in its WRT56G wireless router. This new source distribution (available here; get the 1.41.2 version) contains a good deal of new code, including the modifications to the kernel to support the Broadcom 4702 processor. Many of those who have been pursuing this particular GPL violation case are now satisfied.

The celebration is not universal, however; the new kernel source still lacks the driver for the wireless interface. Unlike the other kernel modifications found in the WRT54G router, the wireless interface is packaged as a separate, binary module. In the eyes of many, that packaging is sufficient to ensure that the driver is not a derived product of the kernel, and, thus, it need not be licensed under the GPL. But not everybody agrees.

The status of binary modules remains the subject of a great deal of confusion; it deserves (yet another) look. There is a widespread impression that Linus Torvalds has issued a blanket exemption to the GPL for closed-source modules. There are only two problems with this idea: (1) it is not entirely true, and (2) the relevance of Linus's opinion is limited. On the first point, consider this pronouncement from Linus, issued almost exactly one year ago:

On the second point, it suffices to remember that Linus is far from the only kernel copyright holder. He made a crucial decision years ago to not require copyright assignments from contributors, and, thus, to allow each contributor to retain copyrights on his or her code. As Linus's role has shifted from coding to rejecting contributions from others, the portion of the kernel code base carrying his copyright has shrunk. Linus can speak for himself, but not for the other kernel copyright holders. And some of the others are getting increasingly grumpy about closed-source modules.

The crucial question here is whether a court would find that a kernel module is a derived product of the kernel itself or not. There is a difference of opinion on that score, to say the least. Eight years ago, Linus suggested that kernel modules, by virtue of the module API which only allowed modules to link to "logically independent" functions within the kernel, were not derived products. As others have pointed out, the list of functions available to modules is rather less controlled these days. 2.6 loadable modules have access to a great many kernel functions (a quick grep turns up over 8000 exported symbols) and require a great deal of inline code from the kernel header files. By some accounts, any code that is so intimately tied into the kernel must be a derived product.

Others have taken the view that anything which can be unplugged and replaced is not a derived product. The existence of a plug-in interface creates a boundary which the GPL cannot cross. In some cases, this must be true; consider, for example, Linuxant's controversial new DriverLoader product. DriverLoader is a proprietary module which will interface Windows NDIS network drivers to the Linux kernel. The legal status of DriverLoader may be unclear, but nobody would argue that a binary Windows driver, when shoehorned into the Linux kernel in this way, becomes a derived product of the kernel. On the other hand, with a small (GPL-licensed) patch, the kernel could be opened to "pluggable" modules implementing proprietary network protocols, memory managers, schedulers, etc. This scheme, if considered legal, would allow proprietary code to be lodged within the heart of the Linux kernel. At that point, there would be no restriction on derived products at all.

Another view, less often heard, notes that the kernel module loader checks the license of every module loaded into the system. If the module lacks a free license, the kernel complains, but loads the module anyway. One could argue that this behavior is an explicit acknowledgment that closed-source modules are permissible.

The only way to get a definitive answer on the location of the GPL boundary will be to go in front of a judge. Even then, the answer is unlikely to be useful beyond the specific case considered there.

In the LinkSys case, some developers are claiming that the source for the binary modules should be released even if they are not strictly seen to be derived products. This claim is based on the following language from section 2 of the General Public License:

Some feel that the LinkSys WRT56G router is, indeed, a "whole which is a work based on the Program" and that the entire system must be licensed under the GPL if it is to be distributed legally. This view relies on the contract provisions of the GPL, and not just on copyright law; it is controversial, to say the least. By this reasoning, a Linux distribution with, say, a proprietary installer could be seen to be violating the GPL. In the end, this claim, too, can only be verified in a courtroom. Until then, the definition of a "whole" is subject to debate.

The status of closed-source modules has always been somewhat unclear, and one gets the impression that the kernel developers have been happy to keep it that way. There is a strong desire to discourage such modules, but, seemingly, little wish to abolish them altogether. The system has worked reasonably well so far, but it may well be asking for trouble in the longer term. With the current state of affairs, it seems certain that, sooner or later, a company or individual holding kernel copyrights will take a proprietary module vendor to court.

One of the best features of free software is the fact that users don't need to worry. The rights of users are broad and well defined; there is no equivalent of the Business Software Alliance looking for companies to raid. The distribution of closed-source kernel modules is an exception, however; nobody really knows if this distribution is legal or not. The free software community is not helped by this uncertainty; it really is past time to clarify the status of closed-source modules. Doing so will be a challenging task, but doing nothing will bring unwanted challenges of its own. The free software community does not need any more litigation, be it instigated by ourselves or by others.

Comments (30 posted)

Two views of the Unix philosophy

We have recently received two books, both of which attempt to set down the Unix philosophy. This philosophy is said to underlie the work we all do with Linux, so discussions of it are worth a look. Maybe we can finally find out what we have been trying to do all these years.

The first is The Art of Unix Programming by Eric Raymond (published by Addison Wesley). We have discussed this book before on these pages, so a detailed look is not necessary at this time. Suffice to say that Eric's book is now available in the stores. It is also available on the net under a relatively restrictive Creative Commons license.

The other entry is Linux and the Unix Philosophy by Mike Gancarz, published by Digital Press. This book appears to be a fairly straightforward remake of Mr. Gancarz's The Unix Philosophy, published in 1994. References to Linux have been retrofitted in, but the book is little changed. If the underlying Unix philosophy is as enduring as these books would have us believe, a book from 1994 should still be current now. Unfortunately, Linux and the Unix Philosophy looks old; consider, for example, the author's advice that a function's parameter list should fit on a single line of an (80-column) screen. That might have been good advice for an old-style C function, but, in the modern world, where parameter names and types all go together, even a very short parameter list can take multiple lines.

This book also ignores many of the features of modern Unix/Linux programming, including scripting languages (beyond the shell) and graphical interfaces. In Mr. Gancarz's view, all programs are small, and their functions are minimal; he even states that multi-column output has bloated the ls command excessively. Or consider:

This discussion does not fit your editor's world, where the best way to improve the performance of a system is often to add memory.

The most interesting area of investigation, however, would be how the two books characterize the Unix philosophy. Happily, both of them provide nice sets of rules suitable for slides in any executive briefing - or a summary table in LWN. So, without further ado...

The Art of Unix Programming	Linux and the Unix Philosophy
Write a big program only when it is clear by demonstration that nothing else will do.	Small is beautiful.
Design for simplicity; add complexity only where you must.	Make each program do one thing well.
Prototype before polishing. Get it working before you optimize it.	Build a prototype as soon as possible.
(No rule, but portability is listed as one of the things Unix got right).	Chose portability over efficiency.
Design programs to be connected with other programs.	Store data in flat text files. Make every program a filter
Avoid hand-hacking; write programs to write programs when you can.	Use software leverage to your advantage. [i.e. reuse code].
Programmer time is expensive; conserve it in preference to machine time.	Use shell scripts to increase leverage and portability.
In interface design, always do the least surprising thing.	Avoid captive user interfaces.
When a program has nothing to say, it should say nothing.	Silence is Golden
	Look for the 90-percent solution. Worse is better.
Design for visibility to make inspection and debugging easier.
Fold knowledge into data so program logic can be stupid and robust.
Repair what you can, but when you must fail, fail noisily and as soon as possible.
Separate policy from mechanism; separate interfaces from engines.
Distrust all claims for the "one true way."

The further expression of these rules shows the relative age and limited scope of Gancarz's book. He talks about flat text files, while Raymond discusses the importance of transparent, textual network protocols as well. Raymond covers the network, modern languages, and the ups and downs of programming techniques as an integral part of his book; Gancarz has a brief "Brave New World" chapter at the end where he treats bleeding-edge technologies like the Internet, artificial intelligence, object-oriented programming, and Java.

On the other side, Eric Raymond's tendencies are well known. The Art of Unix Programming can be verbose and gives a lot of coverage to Mr. Raymond's own work and beliefs. Most people would have found a way to write a Unix book without including quotes from famous people on the evils of gun control, for example.

Both books neglect areas of great concern for any contemporary software developer. Neither will give as much help as the implementer of a web browser, office suite, or DVD player might like. No developer can afford to be unaware of security issues in the current environment, but neither author devotes any space to security. What is the Unix philosophy's approach to security? Silence in response to that question is all too telling.

In the end, if your editor had to choose between the two books, he would go with The Art of Unix Programming, though both have their merits. Readers of either would be well advised to heed Mr. Raymond's last rule, however: distrust anybody who claims to know the "one true way."

Comments (5 posted)

Background on Citizens Against Government Waste

After Citizens Against Government Waste (CAGW) issued a strongly-worded press release against the state of Massachusetts's initiative to move toward open systems, we at LWN decided to take a longer look at this organization's background and see why they might exhibit such hostility toward open source.

According to CAGW's website, the group has been in operation since 1984. It is, according to its press materials "a private, non-partisan, non-profit organization" on a mission to eliminate "waste, mismanagement, and inefficiency in the federal government." It claims to be "nationally recognized as the source of information on government waste," with more than one million members.

Apparently, Microsoft has been one of the corporate donors that provided funding to CAGW in the past. But the group prefers to remain mum on whether Microsoft continues to fund them and what other groups may be providing funding.

We contacted CAGW directly to find out whether Microsoft is still donating money, and how they came to form their opinions on open source use in government. We spoke to CAGW President Tom Schatz, who also declined to specify whether CAGW is still receiving money from Microsoft and said that interested parties could examine CAGW's IRS 990 filing. CAGW is required to make this document available upon request, but is not required to provide the names of its donors.

We located CAGW's filings for 2000 and 2001 online, but the donor information had been whited out. According to CAGW's website, about 85 percent of the organization's funding comes from individual contributors, with the remaining 15 percent coming from corporate and foundation gifts. In 2001, three contributors donated a total of $490,765 to CAGW, accounting for only 10 percent of the non-profit group's entire income of $4,898,720 for the year. In 2000, CAGW brought in $4,846,934 with a single anonymous donor of $150,000. If Microsoft or one of the foundations it supports is still a contributor to CAGW, the contributions are only a minor percentage of overall contributions.

To be sure, CAGW does not exist solely as an apologist or mouthpiece for Microsoft. The organization tracks government spending in many areas unrelated to the software industry, and provides ratings for members of congress, according to their criteria of eliminating government waste.

However, the group has been unrelenting in its opposition to the governments' antitrust suit against Microsoft, and was part of the "grass-roots" effort to stir up public support against the suit. The group made headlines after some of their form letters were mailed in by CAGW members who had died.

When news hit the wires late last month that Massachusetts may be favoring open source, CAGW was quick to oppose the idea -- apparently without bothering to get all the facts on the issue first. Schatz admitted that he later found that, contrary to the position stated in the release, Massachusetts was not barring proprietary vendors from competing for state contracts. Schatz says he will issue a second release with a correction "if something does come out in writing from the state...we've seen quotes, but nothing in writing."

We asked Schatz if he opposes open source software in government, and he replied that he was not opposed to open source software but was opposed to a policy that prefers or requires single-sourcing.

We also asked Schatz about the communist rhetoric contained in their "Mass. Taxpayers Hurt by Proposed Software Monopoly" release. Schatz denied that comparisons of Massachusetts' open source policy were designed to tie in with other comparisons of open source and free software to communism or socialism.

Schatz also mentioned that CAGW group received a number of e-mails from the Linux community on the topic, and had discovered that the community does not appreciate comparisons to communism or socialism. He also noted that CAGW receives strong reactions to many of their releases, not just those on the topic of Linux or open source. A cursory search of CAGW's website did not turn up references to socialism or communism as metaphors for other government waste. The reader can judge for themselves whether the tone in other CAGW releases is similar to the tone of the "Proposed Software Monopoly" release.

It may be that CAGW is poorly informed on the benefits of open source, and too easily swayed by pro-Microsoft studies. Schatz acknowledged that CAGW had not performed any studies independently to determine the cost benefits of open source products versus proprietary software.

It's clear that CAGW carries a substantial amount of influence with a widespread public audience, and with elected officials. Open source advocates would do well to keep tabs on future pronouncements from the group, and to work toward politely educating CAGW on the benefits of free software and the unnecessary waste of government funds on proprietary software.

Comments (7 posted)

Page editor: Jonathan Corbet

Security

Open spam filtering rules considered harmful?

Readers of LWN know that we have long been a fan of SpamAssassin. Your editor, whose personal spam load is approaching 500 messages per day, would long have ceased to function without it. Network life in the 21st century requires either a well-hidden email address, or some sort of effective filtering.

SpamAssassin's extensive arsenal of tests has traditionally included checks for legitimate mail. In the past, mail which identified itself as having been created with certain free email agents or which contained a software patch was given some extra credit in the scoring process. Spammers have often found and exploited those tests; for a while, some of us were receiving mail which had been simultaneously "created" with mutt and evolution. The usual response to such activity has been to remove the tests in question.

Most recently, some spammers have started adding fake PGP signatures (in full HTML glory) to their output, in the hopes of slipping past SpamAssassin. The PGP signature test was removed some time ago, but the exploit was still enough to inspire this News.com article which, among other things, says:

The open nature of SpamAssassin's filtering is, thus, a "danger." Lest one become too concerned about the "dangers" involved in using SpamAssassin, however, there are a few things which should be kept in mind:

• Prospective spam can be tested against any filter, open or closed. It would be surprising if spammers were not trying their products against SpamAssassin in this way. They also, most likely, maintain accounts with large ISPs and try to craft messages that get past the filters those ISPs employ as well.

• SpamAssassin remains highly effective, even when spammers have had plenty of time to study its tests and work out ways to get around it. Open or not, SpamAssassin's rules are very good at identifying spam, and they appear to be hard to get around. Fighting spam is an arms race; it is surprising, actually, how rarely one has to upgrade SpamAssassin to keep it effective.

• The bayesian filtering techniques used by SpamAssassin (and many other spam filtering systems) cannot be worked around in any easy way. A quick test on about 6400 messages which had accumulated in your editor's spam folder shows that the bayesian filter is the decisive test which condemns 15-25% of all incoming spam. Bayesian filters are highly individualized, and they are inaccessible to spammers. The algorithm is entirely open, but that is little comfort to those who would bury us in unwanted trash.

The real lesson from the PGP signature "exploit," most likely, is that negative tests will always be relatively easy for spammers to abuse. That will be why SpamAssassin 2.60 contains almost none of these tests.

The most important point, however, is entirely different. For many of us, email is a vital connection to the world. It is natural to be concerned about trusting a program to filter our incoming mail for us; mistakes can have real consequences. Would you really want to trust your mail to a hidden, proprietary filtering scheme? Don't you want to know what assumptions and biases have gone into the filtering decisions? Or, at least, don't you want that information to be available to those with the time and interest to check it out? Allowing a black box to pass judgment on one's incoming mail stream poses more dangers than an open, free system ever could.

Comments (19 posted)

New vulnerabilities

glibc - buffer overflow

Package(s):	glibc	CVE #(s):	CAN-2003-0689
Created:	October 15, 2003	Updated:	November 25, 2003
Description:	The GNU C library contains a buffer overflow in the getgrouplist() function. If the user belongs to more groups than the calling application expects, the allocated storage will be overrun.
Alerts:	Gentoo 200311-05 2003-11-22 Mandrake MDKSA-2003:107 2003-11-18 Trustix 2003-0039 2003-11-15 Red Hat RHSA-2003:325-01 2003-11-12 Conectiva CLA-2003:762 2003-10-14

Comments (none posted)

tomcat4: denial of service vulnerability

Package(s):	tomcat	CVE #(s):
Created:	October 15, 2003	Updated:	October 15, 2003
Description:	Aldrin Martoq has discovered a denial of service (DoS) vulnerability in Apache Tomcat 4.0.x. Sending several non-HTTP requests to Tomcat's HTTP connector makes Tomcat reject further requests on this port until it is restarted.
Alerts:	Debian DSA-395-1 2003-10-15

Comments (none posted)

Updated vulnerabilities

2.4 kernel - several vulnerabilities

Package(s):	2.4 kernel	CVE #(s):	CAN-2003-0461 CAN-2003-0462 CAN-2003-0464 CAN-2003-0476 CAN-2003-0501 CAN-2003-0550 CAN-2003-0551 CAN-2003-0552
Created:	July 21, 2003	Updated:	December 23, 2003
Description:	Several security issues have been discovered affecting the Linux kernel: CAN-2003-0461: /proc/tty/driver/serial reveals the exact character counts for serial links. This could be used by a local attacker to infer password lengths and inter-keystroke timings during password entry. CAN-2003-0462: Paul Starzetz discovered a file read race condition existing in the execve() system call, which could cause a local crash. CAN-2003-0464: A recent change in the RPC code set the reuse flag on newly-created sockets. Olaf Kirch noticed that his could allow normal users to bind to UDP ports used for services such as nfsd. CAN-2003-0476: The execve system call in Linux 2.4.x records the file descriptor of the executable process in the file table of the calling process, allowing local users to gain read access to restricted file descriptors. CAN-2003-0501: The /proc filesystem in Linux allows local users to obtain sensitive information by opening various entries in /proc/self before executing a setuid program. This causes the program to fail to change the ownership and permissions of already opened entries. CAN-2003-0550: The STP protocol is known to have no security, which could allow attackers to alter the bridge topology. STP is now turned off by default. CAN-2003-0551: STP input processing was lax in its length checking, which could lead to a denial of service. CAN-2003-0552: Jerry Kreuscher discovered that the Forwarding table could be spoofed by sending forged packets with bogus source addresses the same as the local host.
Alerts:	Red Hat RHSA-2003:408-00 2003-12-19 Gentoo 200308-01 2003-08-14 Debian DSA-358-4 2003-08-13 SuSE SuSE-SA:2003:034 2003-08-12 Debian DSA-358-2 2003-08-05 Debian DSA-358-3 2003-08-04 Debian DSA-358-1 2003-07-31 EnGarde ESA-20032407-018 2003-07-24 Red Hat RHSA-2003:238-01 2003-07-21

Comments (none posted)

apache2: Denial of Service vulnerability

Package(s):	apache2	CVE #(s):
Created:	September 29, 2003	Updated:	March 25, 2004
Description:	A problem was discovered in Apache2 where CGI scripts that write more than 4k to the standard error stream will hang the script's execution. This problem can lead to a denial of service situation. See this bug report for additional details.
Alerts:	Gentoo 200403-04 2004-03-22 Netwosix NW-2004-0006 2004-03-25 Mandrake MDKSA-2003:096-1 2003-10-24 Mandrake MDKSA-2003:096 2003-09-26

Comments (none posted)

cfengine: stack overflow

Package(s):	cfengine	CVE #(s):
Created:	October 8, 2003	Updated:	October 8, 2003
Description:	Versions of cfengine prior to 2.0.8 contain a stack overflow in the network I/O code which can be exploited remotely. See this advisory for details.
Alerts:	Gentoo 200310-2 2003-10-04

Comments (none posted)

ethereal: security problems in Ethereal 0.9.12

Package(s):	ethereal	CVE #(s):	CAN-2003-0428 CAN-2003-0429 CAN-2003-0431 CAN-2003-0432
Created:	June 23, 2003	Updated:	November 10, 2003
Description:	Several security problems have been found in Ethereal 0.9.12. "It may be possible to make Ethereal crash or run arbitrary code by injecting a purposefully malformed packet onto the wire, or by convincing someone to read a malformed packet trace file."
Alerts:	SCO Group CSSA-2003-030.0 2003-11-07 Yellow Dog YDU-20030718-2 2003-07-18 Red Hat RHSA-2003:203-01 2003-07-03 Gentoo 200306-13 2003-06-25 Conectiva CLA-2003:662 2003-06-25 Mandrake MDKSA-2003:070 2003-06-23

Comments (none posted)

Filename disclosure vulnerability in fam

Package(s):	fam	CVE #(s):	CAN-2002-0875
Created:	August 19, 2002	Updated:	January 5, 2005
Description:	"fam" (file alteration monitor) watches files and directories for changes and lets interested applications know when something happens. This package has a flaw in its group handling that blocks some legitimate operations while, at the same time, exposing the names of files that should otherwise be invisible.
Alerts:	Red Hat RHSA-2005:005-01 2005-01-05 Debian DSA-154-1 2002-08-15

Comments (none posted)

fetchmail: buffer overflow

Package(s):	fetchmail	CVE #(s):	CAN-2002-1365
Created:	December 17, 2002	Updated:	October 20, 2003
Description:	Versions of fetchmail prior to 6.2.0 have (yet another) buffer overflow vulnerability which can be exploited remotely via a suitably crafted message. See this advisory for details.
Alerts:	Immunix IMNX-2003-7+-023-01 2003-10-17 Mandrake MDKSA-2003:011 2003-01-27 EnGarde ESA-20030127-002 2003-01-27 SCO Group CSSA-2003-001.0 2003-01-09 SuSE SuSE-SA:2003:001 2003-01-02 Debian DSA-216-1 2002-12-24 Red Hat RHSA-2002:293-09 2002-12-17 Conectiva CLA-2002:554 2002-12-16

Comments (3 posted)

glibc: DNS stub resolvers contain buffer overflow vulnerability

Package(s):	glibc	CVE #(s):	CAN-2002-1146
Created:	November 7, 2002	Updated:	February 5, 2004
Description:	DNS stub resolvers from multiple vendors contain a buffer overflow vulnerability. The impact of this vulnerability appears to be limited to denial of service. (See CERT Vulnerability Note VU#738331) The BIND 4 and BIND 8.2.x stub resolver libraries, and other libraries such as glibc 2.2.5 and earlier, libc, and libresolv, uses the maximum buffer size instead of the actual size when processing a DNS response, which causes the stub resolvers to read past the actual boundary ("read buffer overflow"), allowing remote attackers to cause a denial of service (crash).
Alerts:	Mandrake MDKSA-2004:009 2004-02-04 Red Hat RHSA-2002:197-09 2002-11-06 Red Hat RHSA-2002:197-06 2002-10-03

Comments (none posted)

gnupg: key validation

Package(s):	gnupg	CVE #(s):	CAN-2003-0255
Created:	May 15, 2003	Updated:	November 17, 2003
Description:	A key validation bug was discovered in the GNU Privacy Guard (GPG) which would cause keys with more then one user ID to trust all user ID's with the amount of trust given to the most-valid user ID.
Alerts:	SCO Group CSSA-2003-034.0 2003-11-17 Conectiva CLA-2003:694 2003-07-11 Yellow Dog YDU-20030602-4 2003-06-02 Mandrake MDKSA-2003:061 2003-05-22 Slackware ssa:2003-141-04 2003-05-22 Red Hat RHSA-2003:175-01 2003-05-20 Gentoo 200305-04 2003-05-16 OpenPKG OpenPKG-SA-2003.029 2003-05-16 EnGarde ESA-20030515-016 2003-05-15

Comments (none posted)

gtkhtml: malformed messages cause crash

Package(s):	gtkhtml	CVE #(s):	CAN-2003-0133 CAN-2003-0541
Created:	April 14, 2003	Updated:	April 18, 2005
Description:	GtkHTML is the HTML rendering widget used by the Evolution mail reader. GtkHTML supplied with versions of Evolution prior to 1.2.4 contain a bug when handling HTML messages. Alan Cox discovered that certain malformed messages could cause the Evolution mail component to crash.
Alerts:	Debian DSA-710-1 2005-04-18 Mandrake MDKSA-2003:093 2003-09-18 Conectiva CLA-2003:737 2003-09-12 Red Hat RHSA-2003:264-01 2003-09-09 Mandrake MDKSA-2003:046 2003-04-15 Red Hat RHSA-2003:126-01 2003-04-14

Comments (none posted)

KDE: Two issues in KDM

Package(s):	kde, xfree86	CVE #(s):	CAN-2003-0690 CAN-2003-0692
Created:	September 16, 2003	Updated:	December 19, 2003
Description:	According to this advisory two issues have been discovered in KDM: CAN-2003-0690: Privilege escalation with specific PAM modules. The XDM display manager that ships with XFree86 prior to 4.3 is also vulnerable. CAN-2003-0692: Session cookies generated by KDM are potentially insecure All versions of KDM as distributed with KDE up to and including KDE 3.1.3 are affected.
Alerts:	Mandrake MDKSA-2003:118 2003-12-19 Gentoo 200311-01 2003-11-15 Debian DSA-388-1 2003-09-19 Conectiva CLA-2003:747 2003-09-19 Mandrake MDKSA-2003:091 2003-09-16 Red Hat RHSA-2003:269-01 2003-09-16

Comments (none posted)

kernel-utils: setuid vulnerability

Package(s):	kernel-utils	CVE #(s):	CAN-2003-0019
Created:	February 7, 2003	Updated:	January 21, 2005
Description:	The kernel-utils package contains several utilities that can be used to control the kernel or machine hardware. In Red Hat Linux 8.0 this package contains user mode linux (UML) utilities. The uml_net utility in kernel-utils packages with Red Hat Linux 8.0 was incorrectly shipped setuid root. This could allow local users to control certain network interfaces, add and remove arp entries and routes, and put interfaces in and out of promiscuous mode. All users of the kernel-utils package should update to these packages that contain a version of uml_net that is not setuid root. Alternatively, as a work-around to this vulnerability issue the following command as root: chmod -s /usr/bin/uml_net
Alerts:	Red Hat RHSA-2003:056-08 2003-02-07

Comments (none posted)

libpng, libpng3: buffer overflow

Package(s):	libpng, libpng3	CVE #(s):	CAN-2002-1363
Created:	December 19, 2002	Updated:	July 14, 2004
Description:	Glenn Randers-Pehrson discovered a problem in connection with 16-bit samples from libpng, an interface for reading and writing PNG (Portable Network Graphics) format files. The starting offsets for the loops are calculated incorrectly which causes a buffer overrun beyond the beginning of the row buffer.
Alerts:	Gentoo 200407-06 2004-07-08 OpenPKG OpenPKG-SA-2004.030 2004-07-06 Mandrake MDKSA-2004:063 2004-06-29 Whitebox WBSA-2004:249-01 2004-06-21 Fedora FEDORA-2004-176 2004-06-18 Fedora FEDORA-2004-174 2004-06-18 Fedora FEDORA-2004-175 2004-06-18 Fedora FEDORA-2004-173 2004-06-18 Red Hat RHSA-2004:249-01 2004-06-18 Conectiva CLA-2003:564 2003-01-23 Mandrake MDKSA-2003:008 2003-01-20 OpenPKG OpenPKG-SA-2003.001 2003-01-15 Yellow Dog YDU-20030114-2 2002-01-14 SuSE SuSE-SA:2003:0004 2003-01-14 Red Hat RHSA-2003:006-06 2003-01-09 Debian DSA-213-1 2002-12-19

Comments (none posted)

mikmod: buffer overflow

Package(s):	mikmod	CVE #(s):	CAN-2003-0427
Created:	June 16, 2003	Updated:	June 16, 2005
Description:	Ingo Saitz discovered a bug in mikmod whereby a long filename inside an archive file can overflow a buffer when the archive is being read by mikmod.
Alerts:	Fedora FEDORA-2005-405 2005-06-16 Red Hat RHSA-2005:506-01 2005-06-13 Fedora FEDORA-2005-404 2005-06-09 Gentoo 200307-01 2003-07-02 Debian DSA-320-1 2003-06-13

Comments (none posted)

mplayer: remotely exploitable buffer overflow vulnerability

Package(s):	mplayer	CVE #(s):	CAN-2003-0835
Created:	September 29, 2003	Updated:	April 6, 2004
Description:	A remotely exploitable buffer overflow vulnerability was found in MPlayer. A malicious host can craft a harmful ASX header, and trick MPlayer into executing arbitrary code upon parsing that header. Read the full advisory for details.
Alerts:	Mandrake MDKSA-2004:026 2004-04-05 Gentoo 200403-13 2004-03-31 Conectiva CLA-2003:760 2003-10-06 Mandrake MDKSA-2003:097 2003-09-30 Gentoo 200309-15 2003-09-27

Comments (none posted)

mysql: arbitrary code execution

Package(s):	mysql	CVE #(s):	CAN-2003-0780
Created:	September 15, 2003	Updated:	October 9, 2003
Description:	Frank Denis reported a vulnerability in MySQL affecting MySQL3 versions 3.0.57 and earlier and MySQL4 versions 4.0.14 and earlier. Passwords of MySQL users are stored in the "Password" field of the "User" table, part of the "mysql" database. The passwords are hashed and stored as a 16 characters long hexadecimal value. Unfortunately, a function involved in password checking misses correct bounds checking. By filling a "Password" field a value wider than 16 characters, a buffer overflow will occur. The Common Vulnerabilities and Exposures (CVE) project assigned the id CAN-2003-0780 to the problem.
Alerts:	Red Hat RHSA-2003:281-01 2003-10-09 SuSE SuSE-SA:2003:042 2003-10-01 Mandrake MDKSA-2003:094 2003-09-18 Conectiva CLA-2003:743 2003-09-18 EnGarde ESA-20030918-025 2003-09-18 Trustix 2003-0034 2003-09-17 Gentoo 200309-08 2003-09-15 OpenPKG OpenPKG-SA-2003.038 2003-09-15 Debian DSA-381-1 2003-09-13

Comments (none posted)

Nessus NASL scripting engine security issues

Package(s):	nessus	CVE #(s):
Created:	May 27, 2003	Updated:	August 12, 2004
Description:	Some some vulnerabilities exsist in the Nessus NASL scripting engine. To exploit these flaws, an attacker would need to have a valid Nessus account as well as the ability to upload arbitrary Nessus plugins in the Nessus server (this option is disabled by default) or he/she would need to trick a user somehow into running a specially crafted nasl script. Read the full advisory for additional information.
Alerts:	Gentoo 200305-10 2003-05-27

Comments (none posted)

net-snmp: denial of service vulnerability

Package(s):	net-snmp	CVE #(s):	CAN-2002-1170
Created:	December 17, 2002	Updated:	November 7, 2003
Description:	The SNMP daemon included in the Net-SNMP package versions 5.0.1 through 5.0.4 can be caused to crash if it is sent a specially crafted packet.
Alerts:	Conectiva CLA-2003:778 2003-11-07 Red Hat RHSA-2002:228-11 2002-12-17

Comments (none posted)

nfs-utils xlog() off-by-one bug

Package(s):	nfs-utils	CVE #(s):	CAN-2003-0252
Created:	July 14, 2003	Updated:	March 8, 2004
Description:	Linux NFS utils package contains remotely exploitable off-by-one bug. A local or remote attacker could exploit this vulnerability by sending specially crafted request to rpc.mountd daemon. See this BugTraq post for more details.
Alerts:	Trustix TSLSA-2004-0009 2004-03-05 SCO Group CSSA-2003-037.0 2003-11-17 Conectiva CLA-2003:700 2003-07-22 Mandrake MDKSA-2003:076 2003-07-21 Gentoo 200307-07 2003-07-19 Yellow Dog YDU-20030718-1 2003-07-18 Slackware SSA:2003-195-01b 2003-07-15 Immunix IMNX-2003-7+-018-01 2003-07-14 SuSE SuSE-SA:2003:031 2003-07-15 Slackware SSA:2003-195-01 2003-07-14 Debian DSA-349-1 2003-07-14 Red Hat RHSA-2003:206-01 2003-07-14

Comments (none posted)

openssh: timing attack leads to information disclosure

Package(s):	openssh	CVE #(s):	CAN-2003-0190
Created:	May 2, 2003	Updated:	November 30, 2004
Description:	From the advisory: "During a pen-test we stumbled across a nasty bug in OpenSSH-portable with PAM support enabled (via the --with-pam configure script switch). This bug allows a remote attacker to identify valid users on vulnerable systems, through a simple timing attack. The vulnerability is easy to exploit and may have high severity, if combined with poor password policies and other security problems that allow local privilege escalation."
Alerts:	Ubuntu USN-34-1 2004-11-30 OpenPKG OpenPKG-SA-2003.035 2003-08-06 Red Hat RHSA-2003:222-01 2003-07-29 Gentoo 200305-02 2003-05-13 Gentoo 200305-01 2002-03-05

Comments (1 posted)

openssl: vulnerabilities in ASN.1 code

Package(s):	openssl	CVE #(s):	CAN-2003-0543 CAN-2003-0544 CAN-2003-0545
Created:	September 30, 2003	Updated:	November 4, 2003
Description:	Vulnerabilities have been found in OpenSSL ASN.1 code. This advisory contains details of 4 separate problems in versions of OpenSSL up to and including 0.9.6j and 0.9.7b and all versions of SSLeay. An attack against other applications that use OpenSSL could result in a Denial of Service. See CAN-2003-0543 and CAN-2003-0544. It may be possible for an attacker to exploit this issue to execute arbitrary code. See CAN-2003-0545. CERT has an updated OpenSSL advisory identifying additional OpenSSL vulnerabilities.
Alerts:	EnGarde ESA-20031104-029 2003-11-04 Debian DSA-394-1 2003-10-11 Conectiva CLA-2003:759 2003-10-03 EnGarde ESA-20031003-028 2003-10-03 Tawie 2003-0001 2003-10-02 SuSE SuSE-SA:2003:043 2003-10-01 Slackware SSA:2003-273-01 2003-09-30 Mandrake MDKSA-2003:098 2003-09-30 Gentoo 200309-19 2003-10-01 Debian DSA-393-1 2003-10-01 Conectiva CLA-2003:751 2003-09-30 EnGarde ESA-20030930-027 2003-09-30 Immunix IMNX-2003-7+-022-01 2003-09-29 OpenPKG OpenPKG-SA-2003.044 2003-09-30 Red Hat RHSA-2003:292-01 2003-09-30 Red Hat RHSA-2003:291-01 2003-09-30

Comments (none posted)

postfix: denial of service vulnerabilities

Package(s):	postfix	CVE #(s):	CAN-2003-0468 CAN-2003-0540
Created:	August 5, 2003	Updated:	May 27, 2004
Description:	The postfix MTA, versions through 1.1.12 (but not 2.0) is subject to two remotely exploitable denial of service vulnerabilities; see this advisory from Michal Zalewski for details.
Alerts:	Mandrake MDKA-2004:028 2004-05-26 Trustix 2003-0029 2003-08-04 Mandrake MDKSA-2003:081 2003-08-04 EnGarde ESA-20030804-019 2003-08-04 Conectiva CLA-2003:717 2003-08-04 SuSE SuSE-SA:2003:033 2003-08-04 Red Hat RHSA-2003:251-01 2003-08-04 Debian DSA-363-1 2003-08-03

Comments (none posted)

PostgreSQL - more buffer overflows

Package(s):	postgresql	CVE #(s):
Created:	February 12, 2003	Updated:	November 7, 2003
Description:	A new set of buffer overflows has been discovered in PostgreSQL 7.2.2; they affect the circle_poly(), path_encode(), and path_addr() functions. Exploiting these overflows requires that the attacker first obtain a connection to the PostgreSQL server.
Alerts:	Debian DSA-397-1 2003-11-07 Immunix IMNX-2003-7+-005-01 2003-04-08 Trustix 2003-0004 2003-02-20 Mandrake MDKSA-2002:062-1 2003-02-11

Comments (1 posted)

proftpd: remote root shell

Package(s):	proftpd	CVE #(s):	CAN-2003-0831
Created:	September 24, 2003	Updated:	January 2, 2004
Description:	The ASCII translation mechanism in ProFTPD 1.2.8 contains a vulnerability which will provide a remote attacker with a root shell - if the attacker is able to download a specially-crafted file. See this ISS advisory for more information.
Alerts:	Mandrake MDKSA-2003:095-1 2003-12-31 Conectiva CLA-2003:750 2003-09-29 Gentoo 200309-16 2003-09-28 Trustix 2003-0037 2003-09-27 Mandrake MDKSA-2003:095 2003-09-26 OpenPKG OpenPKG-SA-2003.043 2003-09-25 Slackware SSA:2003-259-02 2003-09-23

Comments (2 posted)

Multiple-use vulnerability in Safe.pm

Package(s):	Safe.pm	CVE #(s):	CAN-2002-1323
Created:	October 9, 2002	Updated:	February 20, 2004
Description:	usePerl has a description of a vulnerability in the Safe.pm Perl module. It seems that if a Safe compartment is used more than once, it ceases to be safe. The problem is fixed in Safe 2.08.
Alerts:	SCO Group CSSA-2004-007.0 2004-02-20 Gentoo 200212-6 2002-12-20 Trustix 2002-0087 2002-12-19 OpenPKG OpenPKG-SA-2002.014 2002-12-16 Debian DSA-208-1 2002-12-12

Comments (none posted)

sane-backends: several vulnerabilities

Package(s):	sane-backends	CVE #(s):	CAN-2003-0773 CAN-2003-0774 CAN-2003-0775 CAN-2003-0776 CAN-2003-0777 CAN-2003-0778
Created:	September 11, 2003	Updated:	February 20, 2004
Description:	Alexander Hvostov, Julien Blache and Aurelien Jarno discovered several security-related problems in the sane-backends package, which contains an API library for scanners including a scanning daemon (in the package libsane) that can be remotely exploited. These problems allow a remote attacker to cause a segfault fault and/or consume arbitrary amounts of memory. The attack is successful, even if the attacker's computer isn't listed in saned.conf. You are only vulnerable if you actually run saned e.g. in xinetd or inetd. If the entries in the configuration file of xinetd or inetd respectively are commented out or do not exist, you are safe. Try "telnet localhost 6566" on the server that may run saned. If you get "connection refused" saned is not running and you are safe. The Common Vulnerabilities and Exposures project identifies the following problems: CAN-2003-0773: saned checks the identity (IP address) of the remote host only after the first communication took place (SANE_NET_INIT). So everyone can send that RPC, even if the remote host is not allowed to scan (not listed in saned.conf). CAN-2003-0774: saned lacks error checking nearly everywhere in the code. So connection drops are detected very late. If the drop of the connection isn't detected, the access to the internal wire buffer leaves the limits of the allocated memory. So random memory "after" the wire buffer is read which will be followed by a segmentation fault. CAN-2003-0775: If saned expects strings, it mallocs the memory necessary to store the complete string after it receives the size of the string. If the connection was dropped before transmitting the size, malloc will reserve an arbitrary size of memory. Depending on that size and the amount of memory available either malloc fails (->saned quits nicely) or a huge amount of memory is allocated. Swapping and OOM measures may occur depending on the kernel. CAN-2003-0776: saned doesn't check the validity of the RPC numbers it gets before getting the parameters. CAN-2003-0777: If debug messages are enabled and a connection is dropped, non-null-terminated strings may be printed and segmentation faults may occur. CAN-2003-0778: It's possible to allocate an arbitrary amount of memory on the server running saned even if the connection isn't dropped. At the moment this can not easily be fixed according to the author. Better limit the total amount of memory saned may use (ulimit).
Alerts:	SCO Group CSSA-2004-005.0 2004-02-19 SuSE SuSE-SA:2003:046 2003-11-18 Conectiva CLA-2003:769 2003-10-22 Mandrake MDKSA-2003:099 2003-10-09 Red Hat RHSA-2003:278-01 2003-10-07 Debian DSA-379-1 2003-09-11

Comments (none posted)

sendmail: remotely exploitable buffer overflow

Package(s):	sendmail	CVE #(s):	CAN-2003-0694 CAN-2003-0681
Created:	September 17, 2003	Updated:	November 18, 2003
Description:	Michal Zalewski has reported a buffer overflow in sendmail. This overflow, apparently, may be exploited remotely, but only in certain (non-default) configurations. Sendmail 8.12.10 has the fix.
Alerts:	SCO Group CSSA-2003-036.0 2003-11-17 SuSE SuSE-SA:2003:040 2003-09-20 OpenPKG OpenPKG-SA-2003.041 2003-09-19 Conectiva CLA-2003:742 2003-09-18 Yellow Dog YDU-20030917-2 2003-09-17 Immunix IMNX-2003-7+-021-01 2003-09-17 Mandrake MDKSA-2003:092 2003-09-17 Debian DSA-384-1 2003-09-17 Red Hat RHSA-2003:283-01 2003-09-17 Slackware SSA:2003-260-02 2003-09-17 Gentoo 200309-13 2003-09-17

Comments (none posted)

stunnel: signal handler reentrancy DoS

Package(s):	stunnel	CVE #(s):	CAN-2002-1563
Created:	July 25, 2003	Updated:	November 25, 2003
Description:	Stunnel is a wrapper for network connections. It can be used to tunnel an unencrypted network connection over a secure connection (encrypted using SSL or TLS) or to provide a secure means of connecting to services that do not natively support encryption. When configured to listen for incoming connections (instead of being invoked by xinetd), stunnel can be configured to either start a thread or a child process to handle each new connection. If Stunnel is configured to start a new child process to handle each connection, it will receive a SIGCHLD signal when that child exits. Stunnel versions prior to 4.04 would perform tasks in the SIGCHLD signal handler which, if interrupted by another SIGCHLD signal, could be unsafe. This could lead to a denial of service.
Alerts:	Red Hat RHSA-2003:296-01 2003-11-24 SCO Group CSSA-2003-026.0 2003-10-03 Conectiva CLA-2003:736 2003-09-05 Trustix 2003-0030 2003-08-07 EnGarde ESA-20030806-020 2003-08-06 Red Hat RHSA-2003:221-01 2003-07-25

Comments (none posted)

File overwrite vulnerability in tar and unzip

Package(s):	tar unzip	CVE #(s):	CAN-2001-1267 CAN-2001-1268 CAN-2001-1269 CAN-2002-0399
Created:	October 1, 2002	Updated:	April 9, 2006
Description:	The tar utility does not properly filter file names containing "../", meaning that a hostile archive can, if unpacked by an unsuspecting user, overwrite any file that is writable by that user. GNU tar versions 1.13.19 and earlier are vulnerable; unzip through version 5.42 has the same vulnerability.
Alerts:	Fedora-Legacy FLSA:183571-1 2006-04-04 Red Hat RHSA-2006:0195-01 2006-02-21 Conectiva CLA-2002:538 2002-10-29 Mandrake MDKSA-2002:066 2002-10-10 Mandrake MDKSA-2002:065 2002-10-10 EnGarde ESA-20021003-022 2002-10-03 Gentoo unzip-20021001 2002-10-01 Gentoo tar-20021001 2002-10-01 Red Hat RHSA-2002:096-24 2002-09-18

Comments (1 posted)

Multiple vendor telnetd vulnerability

Package(s):	telnet Telnet netkit-telnet-ssl kerberos telnetd netkit-telnet nkitb/nkitserv/telnetd krb5	CVE #(s):
Created:	May 20, 2002	Updated:	October 5, 2004
Description:	This vulnerability, originally thought to be confined to BSD-derived systems, was first covered in the July 26th Security Summary. It is now known that Linux telnet daemons are vulnerable as well.
Alerts:	Gentoo 200410-03 2004-10-05 Yellow Dog YDU-20010810-2 2001-08-10 Yellow Dog YDU-20010810-1 2001-08-10 SuSE SuSE-SA:2001:029 2001-09-03 Slackware sl-997726350 2001-08-09 Red Hat RHSA-2001:100-02 2001-08-09 Red Hat RHSA-2001:099-09 2002-02-07 Red Hat RHSA-2001:099-06 2001-08-09 Progeny PROGENY-SA-2001-27 2001-08-14 Mandrake MDKSA-2001:093 2001-12-17 Mandrake MDKSA-2001:068 2001-08-13 HP HPSBTL0202-023 2002-02-12 Debian DSA-075-2 2001-08-14 Debian DSA-075-1 2001-08-14 Conectiva CLA-2001:413 2001-08-24 SCO Group CSSA-2001-030.0 2001-08-10

Comments (none posted)

unzip: directory traversal vulnerability

Package(s):	unzip	CVE #(s):	CAN-2003-0282
Created:	July 1, 2003	Updated:	November 13, 2003
Description:	A vulnerabilitiy in unzip version 5.50 and earlier allows attackers to overwrite arbitrary files during archive extraction by placing invalid (non-printable) characters between two "." characters. These non-printable characters are filtered, resulting in a ".." sequence. See the full advisory for further information.
Alerts:	SCO Group CSSA-2003-031.0 2003-11-07 Debian DSA-344-2 2003-08-26 Slackware SSA:2003-237-01 2003-08-25 Mandrake MDKSA-2003:073-1 2003-08-19 Conectiva CLA-2003:724 2003-08-18 Red Hat RHSA-2003:199-02 2003-08-15 Yellow Dog YDU-20030710-1 2003-07-10 Gentoo 200307-02 2003-07-11 OpenPKG OpenPKG-SA-2003.033 2003-07-10 Debian DSA-344-1 2003-07-08 Mandrake MDKSA-2003:073 2003-07-07 Conectiva CLA-2003:672 2003-07-02 Immunix IMNX-2003-7+-017-01 2003-07-02 Red Hat RHSA-2003:199-01 2003-07-01

Comments (none posted)

vim - modeline vulnerability

Package(s):	vim	CVE #(s):	CAN-2002-1377
Created:	January 16, 2003	Updated:	February 10, 2004
Description:	VIM allows a user to set the modeline differently for each edited text file by placing special comments in the files. Georgi Guninski found that these comments can be carefully crafted in order to call external programs. This could allow an attacker to create a text file such that when it is opened arbitrary commands are executed.
Alerts:	Conectiva CLA-2004:812 2004-02-10 Mandrake MDKSA-2003:012 2003-02-03 Yellow Dog YDU-20030127-3 2003-01-27 Gentoo 200301-13 2003-01-22 OpenPKG OpenPKG-SA-2003.003 2003-01-21 Red Hat RHSA-2002:297-17 2003-01-15

Comments (4 posted)

webmin: session ID spoofing

Package(s):	webmin	CVE #(s):	CAN-2003-0101
Created:	June 13, 2003	Updated:	November 18, 2003
Description:	miniserv.pl in the webmin package does not properly handle metacharacters, such as line feeds and carriage returns, in Base64-encoded strings used in Basic authentication. This vulnerability allows remote attackers to spoof a session ID, and thereby gain root privileges.
Alerts:	SCO Group CSSA-2003-035.0 2003-11-17 Debian DSA-319-1 2003-06-12

Comments (none posted)

wget: buffer overflow

Package(s):	wget	CVE #(s):	CAN-2003-1565
Created:	August 5, 2003	Updated:	December 10, 2003
Description:	The wget utility contains a buffer overflow which, when exploited with an over-long URL, can enable arbitrary code execution.
Alerts:	Red Hat RHSA-2003:372-01 2003-12-10 SCO Group CSSA-2003-025.0 2003-10-03 Conectiva CLA-2003:716 2003-08-04

Comments (1 posted)

XFree86 4.3.0 integer overflows in font libraries

Package(s):	XFree86	CVE #(s):	CAN-2003-0730
Created:	September 12, 2003	Updated:	November 25, 2003
Description:	Several vulnerabilities were discovered by blexim(at)hush.com in the font libraries of XFree86 version 4.3.0 and earlier. These bugs could potentially lead to execution of arbitrary code or a DoS by a remote user in any way that calls these functions, which are related to the transfer and enumeration of fonts from font servers to clients. See the advisory for additional details.
Alerts:	Red Hat RHSA-2003:286-01 2003-11-25 Red Hat RHSA-2003:287-01 2003-11-25 Red Hat RHSA-2003:288-01 2003-11-17 Debian DSA-380-1 2003-09-12 Mandrake MDKSA-2003:089 2003-09-11

Comments (none posted)

xinetd: Memory leak in xinetd 2.3.10

Package(s):	xinetd	CVE #(s):	CAN-2003-0211
Created:	May 13, 2003	Updated:	November 12, 2003
Description:	Xinetd is a 'master server' that is used to to accept service connection requests and start the appropriate servers. Because of a programming error, memory was allocated and never freed if a connection was refused for any reason. An attacker could exploit this flaw to crash the xinetd server, rendering all services it controls unavailable. In addition, other flaws in xinetd could cause incorrect operation in certain unusual server configurations. All users of xinetd are advised to update to xinetd-2.3.11 which is not vulnerable to these issues.
Alerts:	Conectiva CLA-2003:782 2003-11-12 Yellow Dog YDU-20030602-1 2003-06-02 Gentoo 200305-08 2003-05-19 Mandrake MDKSA-2003:056 2003-05-14 Red Hat RHSA-2003:160-01 2003-05-13

Comments (none posted)

Resources

This month's CRYPTO-GRAM

Bruce Schneier's CRYPTO-GRAM newsletter for October is out. This month's topics include the future of surveillance, the expanding use of the "Patriot" act, pirating movies, identity cards, and the security risks of monocultures. "The upshot of this is that you should consider the possibility, albeit remote, that you are being observed whenever you're out in public. Assume that all public Internet terminals are being eavesdropped on; either don't use them or don't care. Assume that cameras are watching and recording you as you walk down the street. (In some cities, they probably are.) Assume that surveillance technologies that were science fiction ten years ago are now mass-market."

Full Story (comments: 2)

Linux Security Week

The October 14 issue of Linux Security Week from LinuxSecurity.com is available.

Full Story (comments: none)

New CERT Coordination Center (CERT/CC) PGP Key

CERT has adopted a new PGP key which will be used in its outgoing email. See the announcement for details on how to get the new key. Apparently the passphrase for the previous key was spread a little more widely than CERT had intended.

Full Story (comments: none)

Events

FIRST Conference

The 16th Forum of Incident Response and Security Teams (FIRST) will be held June 13 to 18 in Budapest, Hungary. The call for papers is out now, with a submission deadline of December 1.

Full Story (comments: none)

Page editor: Jonathan Corbet

Kernel development

Release status

Kernel release status

The current development kernel is 2.6.0-test7; there have been no development kernel releases in the last week.

Linus's BitKeeper tree does contain a pile of patches, most of which are stability fixes as one would expect. It also includes a (controversial) patch to allow kernel threads to handle signals properly, a fix for a possible interrupt handling deadlock, and a workaround for the AMD Opteron prefetch bug.

The current stable kernel is 2.4.22. Marcelo released 2.4.23-pre7 on October 9; it includes Jens Axboe's laptop mode patch, a new MegaRAID driver, BIOS enhanced disk detection support, USB gadget support, and various other fixes and updates. The plan is apparently to get the first release candidate out within a month.

Comments (1 posted)

Kernel development news

Looking forward to 2.7

Some attention has been given to the "2.7 thoughts" list which has been circulating on linux-kernel. Looking forward to what can be done in the next development series can be an interesting exercise. In this case, though, the exercise has mostly been carried out by people who will not actually be doing the work; as a result, the list has been dismissed by a few kernel hackers; one called it "crackpot wishlist gunk."

So what are the crackpots wishing for? Some of the items they want (marked "mandatory features" on the list) are already in the works; these include support for CPU hotplugging, full NTFS support and virtual machine support. Others are somewhat vague, including "complete user quota centralization" and "improve kobject model for security, quota rendering." And some will never happen; there is just not a whole lot of call for features like an in-kernel Gopher server or a /proc implementation of the loadable module tools.

Kernel hackers have far more respect for code (and those who produce it) than they do for list makers. The 2.7 thoughts list may yet inspire somebody to do some hacking, but its influence on the development process is likely to remain small.

A more interesting view into what could happen with 2.7 might be found in a conversation between Linus and Joel Becker of Oracle. The discussion turned to what information was needed from the kernel to perform direct I/O, which lead to this outburst from Linus:

Linus went on to wish an early death upon disk-based databases; he seems to think that all but the largest databases should just be done in-memory.

Direct I/O does bring its share of problems. It is hard to keep the kernel page cache in a coherent condition when I/O operations are allowed to circumvent it; page cache confusion can lead to corrupted data. Getting good performance out of direct I/O is hard unless asynchronous I/O is used as well. Direct I/O can also confuse the disk I/O scheduler by creating request patterns (especially overlapping requests) which don't otherwise happen. In other words, the direct I/O idea is hard to get right for both kernel and user space.

But systems like Oracle do need some of the capabilities that direct I/O provides. They need to be able to move large amounts of data without polluting the page cache with stuff that will not be used. Databases which use shared storage need to be able to force data to be reread from disk when another system has changed it. Large applications also tend to have a better idea of how their access patterns work than the kernel does; they know when a particular block of data will not be used any more. The need for the level of control and performance direct I/O can provide will persist, whether it