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authorLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 08:36:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 08:36:04 -0800
commit09884964335e85e897876d17783c2ad33cf8a2e0 (patch)
tree4cf0ea71bb20c8d81147614e90e53df3368405e5 /drivers/hv
parentd895cb1af15c04c522a25c79cc429076987c089b (diff)
mm: do not grow the stack vma just because of an overrun on preceding vma
The stack vma is designed to grow automatically (marked with VM_GROWSUP or VM_GROWSDOWN depending on architecture) when an access is made beyond the existing boundary. However, particularly if you have not limited your stack at all ("ulimit -s unlimited"), this can cause the stack to grow even if the access was really just one past *another* segment. And that's wrong, especially since we first grow the segment, but then immediately later enforce the stack guard page on the last page of the segment. So _despite_ first growing the stack segment as a result of the access, the kernel will then make the access cause a SIGSEGV anyway! So do the same logic as the guard page check does, and consider an access to within one page of the next segment to be a bad access, rather than growing the stack to abut the next segment. Reported-and-tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/hv')
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