diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-04-07 07:35:50 -0700 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2011-04-30 16:53:28 +0200 |
| commit | 130d82a534d65c3895ab65e6d309c3609890ddfc (patch) | |
| tree | 62fdde5b462898b389b32bbf25bc3f4c60eaa46c | |
| parent | 485561dabd3e98bb5540e18ce23dae1b08fd18ac (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>
[wt: 2.6.27 has this code in do_mremap()]
| -rw-r--r-- | mm/mremap.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index 63782eb8e5a8..a27c00798c26 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -333,10 +333,21 @@ unsigned long do_mremap(unsigned long addr, /* We can't remap across vm area boundaries */ if (old_len > vma->vm_end - addr) goto out; - 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 out; + pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; + pgoff += vma->vm_pgoff; + if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) { + ret = -EINVAL; + goto out; + } } + if (vma->vm_flags & VM_LOCKED) { unsigned long locked, lock_limit; locked = mm->locked_vm << PAGE_SHIFT; |