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Commit dcd4a049 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: check for no mmaps in exit_mmap() 



When dup_mmap() ooms we can end up with mm->mmap == NULL.  The error
path does mmput() and unmap_vmas() gets a NULL vma which it
dereferences.

In exit_mmap() there is nothing to do at all for this case, we can
cancel the callpath right there.

[akpm@linux-foundation.org: add sorely-needed comment]
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reported-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 084f71ae

mm/mmap.c

+3 −0
Original line number Diff line number Diff line
@@ -2090,6 +2090,9 @@ void exit_mmap(struct mm_struct *mm) 
	arch_exit_mmap(mm);

	mmu_notifier_release(mm);



	if (!mm->mmap)	/* Can happen if dup_mmap() received an OOM */

		return;



	if (mm->locked_vm) {

		vma = mm->mmap;

		while (vma) {