linux-kernel - [PATCH 0/1] Re: kernel BUG at fs/userfaultfd.c:LINE!

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Date:   Sat, 23 Dec 2017 01:25:04 +0100
From:   Andrea Arcangeli <aarcange@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Eric Biggers <ebiggers3@...il.com>
Cc:     Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        viro@...iv.linux.org.uk, linux-mm@...ck.org,
        syzkaller-bugs@...glegroups.com
Subject: [PATCH 0/1] Re: kernel BUG at fs/userfaultfd.c:LINE!

Hello,

Thanks for the CC, I'm temporarily very busy so if there's something
urgent, safer to CC.

This passed both testcases, the hard part was already done. I'm glad
there was nothing wrong in the previous fix that had to be redone.

Simply we forgot to undo the vma->vm_userfaultfd_ctx = NULL after
aborting the new child uffd ctx, the original code of course didn't do
that either.

Having just seen this issue, this isn't very well tested.

Thank you,
Andrea

Andrea Arcangeli (1):
  userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK
    fails

 fs/userfaultfd.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)