3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Michael S. Tsirkin" <m...@redhat.com>
[ Upstream commit c38e39c378f46f00ce922dd40a91043a9925c28d ]
vhost_net_ubuf_put_and_wait has a confusing name:
it will actually also free it's argument.
Thus since commit 1280c27f8e29acf4af2da914e80ec27c3dbd5c01
"vhost-net: flush outstanding DMAs on memory change"
vhost_net_flush tries to use the argument after passing it
to vhost_net_ubuf_put_and_wait, this results
in use after free.
To fix, don't free the argument in vhost_net_ubuf_put_and_wait,
add an new API for callers that want to free ubufs.
Acked-by: Asias He <as...@redhat.com>
Acked-by: Jason Wang <jasow...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/vhost/net.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -150,6 +150,11 @@ static void vhost_net_ubuf_put_and_wait(
{
kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
+}
+
+static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
+{
+ vhost_net_ubuf_put_and_wait(ubufs);
kfree(ubufs);
}
@@ -948,7 +953,7 @@ static long vhost_net_set_backend(struct
mutex_unlock(&vq->mutex);
if (oldubufs) {
- vhost_net_ubuf_put_and_wait(oldubufs);
+ vhost_net_ubuf_put_wait_and_free(oldubufs);
mutex_lock(&vq->mutex);
vhost_zerocopy_signal_used(n, vq);
mutex_unlock(&vq->mutex);
@@ -966,7 +971,7 @@ err_used:
rcu_assign_pointer(vq->private_data, oldsock);
vhost_net_enable_vq(n, vq);
if (ubufs)
- vhost_net_ubuf_put_and_wait(ubufs);
+ vhost_net_ubuf_put_wait_and_free(ubufs);
err_ubufs:
fput(sock->file);
err_vq:
--
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