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| author | Luiz Capitulino <lcapitulino@redhat.com> | 2013-07-02 15:35:13 +0930 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-07-25 14:07:31 -0700 |
| commit | ebfc049ce8e32b5ff6bf6fec74775ac021769f37 (patch) | |
| tree | ae447ceae1642cf9bc5649082b2b448cb6ae0740 | |
| parent | 0531603e3a0dbb7c36f2b37833add0e73b8c0c5f (diff) | |
| download | lwn-ebfc049ce8e32b5ff6bf6fec74775ac021769f37.tar.gz lwn-ebfc049ce8e32b5ff6bf6fec74775ac021769f37.zip | |
virtio_balloon: leak_balloon(): only tell host if we got pages deflated
commit 8c6bab4f3874d31804a00782c48a8f244a0d3cc0 upstream.
balloon_page_dequeue() can return NULL. If it does for the first page
being freed then leak_balloon() will create a scatter list with len=0.
Which in turn seems to generate an invalid virtio request.
I didn't get this in practice, I found it by code review. On the other
hand, such an invalid virtio request will cause errors in QEMU and
fill_balloon() also performs the same check implemented by this commit.
This bug was introduced in e2250429.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index bd3ae324a1a2..71af7b5abe01 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -191,7 +191,8 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); * is true, we *have* to do it in this order */ - tell_host(vb, vb->deflate_vq); + if (vb->num_pfns != 0) + tell_host(vb, vb->deflate_vq); mutex_unlock(&vb->balloon_lock); release_pages_by_pfn(vb->pfns, vb->num_pfns); } |