User: Password:
|
|
Subscribe / Log in / New account

Tainting from user space

Tainting from user space

Posted May 25, 2006 8:07 UTC (Thu) by ncm (subscriber, #165)
Parent article: Tainting from user space

What keeps somebody from writing Java code that un-taints the kernel? Cooperativeness?


(Log in to post comments)

Tainting from user space

Posted May 25, 2006 10:35 UTC (Thu) by remijnj (guest, #5838) [Link]

I think tainting is a one-way street and that a kernel can't be untainted. The article doesn't mention that writing '0' to the sysfs file untaints it.

Tainting from user space

Posted May 25, 2006 11:40 UTC (Thu) by schabi (guest, #14079) [Link]

But given access to the whole _physical_ memory allows one to reset the taint flag.

Tainting from user space

Posted May 25, 2006 12:52 UTC (Thu) by remijnj (guest, #5838) [Link]

Hmmm, didn't think of that. You are ofcourse correct. If a user space process has access to physical memory all bets are off.

Tainting from user space

Posted May 25, 2006 14:12 UTC (Thu) by elanthis (guest, #6227) [Link]

What would be the purpose of doing this, though? The only thing it would allow is wasting a little kernel developer time when a bug report is submitted. Whoopee.

Second, setting that flag by poking around memory probably isn't that easy. Where in memory is the flag, exactly? With how every kernel release (and almost every kernel compilation) can end up with pretty drastically different memory layouts, it's not possible to just write some data to some specific memory location. You would have to write an awful lot of very complex code just to figure out where to write the change. And if the code isn't absolutely right, you probably just end up crashing the machine. (And, hence, if you do a bug report of the oops message, it shows developers the kernel was tainted.)


Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds