Messages in this thread | | | Date | Wed, 22 Sep 2021 10:30:53 -0400 | From | Peter Xu <> | Subject | Re: [PATCH] userfaultfd: fix a race between writeprotect and exit_mmap() |
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On Tue, Sep 21, 2021 at 01:02:47PM -0700, Nadav Amit wrote: > From: Nadav Amit <namit@vmware.com> > > A race is possible when a process exits, its VMAs are removed > by exit_mmap() and at the same time userfaultfd_writeprotect() is > called. > > The race was detected by KASAN on a development kernel, but it appears > to be possible on vanilla kernels as well. > > Use mmget_not_zero() to prevent the race as done in other userfaultfd > operations. > > Cc: Peter Xu <peterx@redhat.com> > Cc: Andrea Arcangeli <aarcange@redhat.com> > Cc: stable@vger.kernel.org > Fixes: 63b2d4174c4ad ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl") > Signed-off-by: Nadav Amit <namit@vmware.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Thanks!
-- Peter Xu
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