tree 32aae4719abbd338864ab6faf9e8ebbfc38b1600
parent 6221f222c0ebf1acdf7abcf927178f40e1a65e2a
author Linus Torvalds <torvalds@linux-foundation.org> 1302186950 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1302186951 -0700

mm: avoid wrapping vm_pgoff in mremap()

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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>