Commit b99eaefb authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Greg Kroah-Hartman

userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered

commit 01e881f5 upstream.

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.

Link: http://lkml.kernel.org/r/20181206212028.18726-2-aarcange@redhat.com
Cc: <stable@vger.kernel.org>
Fixes: 29ec9066 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas")
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5f4610fe
......@@ -1567,7 +1567,6 @@ 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
......@@ -1576,6 +1575,8 @@ 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);
......
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