Messages in this thread | | | Date | Thu, 6 Dec 2018 23:32:12 +0200 | From | Mike Rapoport <> | Subject | Re: [PATCH 1/1] userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered |
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On Thu, Dec 06, 2018 at 04:20:28PM -0500, Andrea Arcangeli wrote: > Calling UFFDIO_UNREGISTER on virtual ranges not yet registered in uffd > could trigger an harmless false positive WARN_ON. Check the vma is > already registered before checking VM_MAYWRITE to shut off the > false positive warning. > > Cc: <stable@vger.kernel.org> > Fixes: 29ec90660d68 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas") > Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
> --- > fs/userfaultfd.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index cd58939dc977..7a85e609fc27 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1566,7 +1566,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > cond_resched(); > > BUG_ON(!vma_can_userfault(vma)); > - WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); > > /* > * Nothing to do: this vma is already registered into this > @@ -1575,6 +1574,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > if (!vma->vm_userfaultfd_ctx.ctx) > goto skip; > > + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); > + > if (vma->vm_start > start) > start = vma->vm_start; > vma_end = min(end, vma->vm_end); >
-- Sincerely yours, Mike.
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