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vm: fix vm_pgoff wrap in stack expansion
Commit 982134ba62
("mm: avoid wrapping vm_pgoff in mremap()") fixed
the case of a expanding mapping causing vm_pgoff wrapping when you used
mremap. But there was another case where we expand mappings hiding in
plain sight: the automatic stack expansion.
This fixes that case too.
This one also found by Robert Święcki, using his nasty system call
fuzzer tool. Good job.
Reported-and-tested-by: Robert Święcki <robert@swiecki.net>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
60d48c1e67
commit
a626ca6a65
13
mm/mmap.c
13
mm/mmap.c
@ -1814,11 +1814,14 @@ static int expand_downwards(struct vm_area_struct *vma,
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size = vma->vm_end - address;
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grow = (vma->vm_start - address) >> PAGE_SHIFT;
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error = acct_stack_growth(vma, size, grow);
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if (!error) {
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vma->vm_start = address;
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vma->vm_pgoff -= grow;
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perf_event_mmap(vma);
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error = -ENOMEM;
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if (grow <= vma->vm_pgoff) {
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error = acct_stack_growth(vma, size, grow);
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if (!error) {
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vma->vm_start = address;
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vma->vm_pgoff -= grow;
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perf_event_mmap(vma);
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}
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}
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}
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vma_unlock_anon_vma(vma);
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