diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-04-07 07:35:50 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-04-14 16:53:30 -0700 |
| commit | d7c75177f0cae6bb0ec22d2180076f46c5d4d362 (patch) | |
| tree | e52c22cb5f381b9c783f97f7cf49526d7b75b57f /mm | |
| parent | 8975a50e80906e43575b419f7849d251311a2067 (diff) | |
mm: avoid wrapping vm_pgoff in mremap()
commit 982134ba62618c2d69fbbbd166d0a11ee3b7e3d8 upstream.
The normal mmap paths all avoid creating a mapping where the pgoff
inside the mapping could wrap around due to overflow. However, an
expanding mremap() can take such a non-wrapping mapping and make it
bigger and cause a wrapping condition.
Noticed by Robert Swiecki when running a system call fuzzer, where it
caused a BUG_ON() due to terminally confusing the vma_prio_tree code. A
vma dumping patch by Hugh then pinpointed the crazy wrapped case.
Reported-and-tested-by: Robert Swiecki <robert@swiecki.net>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mremap.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index 166b824c2066..3e98d79f5589 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -275,9 +275,16 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, if (old_len > vma->vm_end - addr) goto Efault; - if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { - if (new_len > old_len) + /* Need to be careful about a growing mapping */ + if (new_len > old_len) { + unsigned long pgoff; + + if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) goto Efault; + pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; + pgoff += vma->vm_pgoff; + if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) + goto Einval; } if (vma->vm_flags & VM_LOCKED) { |