Null pointers, one month later

Null pointers, one month later

Posted Aug 18, 2009 17:56 UTC (Tue) by fuhchee (subscriber, #40059)
In reply to: Null pointers, one month later by cruff
Parent article: Null pointers, one month later

Why don't they just force the use of the no-execute page table (on processors that support it) for all kernel mappings of user space?

Perhaps that would destroy the performance benefits of sharing the VM information between kernel & user space (since the flag would have to be toggled on & off).

Then there would be no way cause the execution of user code even if there are additional missing NULL pointer checks?

There's also "return-oriented programming", a technique for breaking into even suchly configured machines.

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