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authorAndrea Arcangeli <aarcange@redhat.com>2018-12-14 14:17:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-14 15:05:45 -0800
commit01e881f5a1fca4677e82733061868c6d6ea05ca7 (patch)
tree104ce9922663f88b905b14ecacc2c710367b48a9
parent61c6de667263184125d5ca75e894fcad632b0dd3 (diff)
userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered
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: 29ec90660d68 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/userfaultfd.c3
1 files changed, 2 insertions, 1 deletions
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);

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