userfaultfd: remove uffd flags from vma->vm_flags if UFFD_EVENT_FORK fails
The fix in commit 0cbb4b4f ("userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK fails") cleared the vma->vm_userfaultfd_ctx but kept userfaultfd flags in vma->vm_flags that were copied from the parent process VMA. As the result, there is an inconsistency between the values of vma->vm_userfaultfd_ctx.ctx and vma->vm_flags which triggers BUG_ON in userfaultfd_release(). Clearing the uffd flags from vma->vm_flags in case of UFFD_EVENT_FORK failure resolves the issue. Link: http://lkml.kernel.org/r/1532931975-25473-1-git-send-email-rppt@linux.vnet.ibm.com Fixes: 0cbb4b4f ("userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK fails") Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reported-by: <syzbot+121be635a7a35ddb7dcb@syzkaller.appspotmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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