This is a note to let you know that I've just added the patch titled
virtio_balloon: leak_balloon(): only tell host if we got pages deflated
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio_balloon-leak_balloon-only-tell-host-if-we-got-pages-deflated.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8c6bab4f3874d31804a00782c48a8f244a0d3cc0 Mon Sep 17 00:00:00 2001
From: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
Date: Tue, 2 Jul 2013 15:35:13 +0930
Subject: virtio_balloon: leak_balloon(): only tell host if we got pages deflated
From: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -191,7 +191,8 @@ static void leak_balloon(struct virtio_b
* 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);
}
Patches currently in stable-queue which might be from lcapitulino@xxxxxxxxxx are
queue-3.10/virtio_balloon-leak_balloon-only-tell-host-if-we-got-pages-deflated.patch
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