userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK fails
authorAndrea Arcangeli <aarcange@redhat.com>
Fri, 5 Jan 2018 00:18:09 +0000 (16:18 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 5 Jan 2018 00:45:09 +0000 (16:45 -0800)
commit0cbb4b4f4c44f54af268969b18d8deda63aded59
treee4195e9d5425397f557117077d6306eadf94e350
parentd09cfbbfa0f761a97687828b5afb27b56cbf2e19
userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK fails

The previous fix in commit 384632e67e08 ("userfaultfd: non-cooperative:
fix fork use after free") corrected the refcounting in case of
UFFD_EVENT_FORK failure for the fork userfault paths.

That still didn't clear the vma->vm_userfaultfd_ctx of the vmas that
were set to point to the aborted new uffd ctx earlier in
dup_userfaultfd.

Link: http://lkml.kernel.org/r/20171223002505.593-2-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/userfaultfd.c