Add vhost-net use-after-free fix (rhbz 976789 980643)

2 files changed, 83 insertions, 0 deletions

diff --git a/kernel.spec b/kernel.spec
index c39fa225e..4964dc5d5 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -794,6 +794,9 @@ Patch25055: ath3k-dont-use-stack-memory-for-DMA.patch
 Patch25056: iwl3945-better-skb-management-in-rx-path.patch
 Patch25057: iwl4965-better-skb-management-in-rx-path.patch
 
+#rhbz 976789 980643
+Patch25062: vhost-net-fix-use-after-free-in-vhost_net_flush.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1512,6 +1515,9 @@ ApplyPatch ath3k-dont-use-stack-memory-for-DMA.patch
 ApplyPatch iwl3945-better-skb-management-in-rx-path.patch
 ApplyPatch iwl4965-better-skb-management-in-rx-path.patch
 
+#rhbz 976789 980643
+ApplyPatch vhost-net-fix-use-after-free-in-vhost_net_flush.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2309,6 +2315,7 @@ fi
 #                 ||     ||
 %changelog
 * Fri Jul 05 2013 Josh Boyer <jwboyer@redhat.com>
+- Add vhost-net use-after-free fix (rhbz 976789 980643)
 - Add fix for timer issue in bridge code (rhbz 980254)
 
 * Wed Jul 03 2013 Josh Boyer <jwboyer@redhat.com>
diff --git a/vhost-net-fix-use-after-free-in-vhost_net_flush.patch b/vhost-net-fix-use-after-free-in-vhost_net_flush.patch
new file mode 100644
index 000000000..b90095e54
--- /dev/null
+++ b/vhost-net-fix-use-after-free-in-vhost_net_flush.patch
@@ -0,0 +1,76 @@
+Date:	Tue, 25 Jun 2013 17:29:46 +0300
+From:	"Michael S. Tsirkin" <mst@redhat.com>
+To:	linux-kernel@vger.kernel.org
+Cc:	"David S. Miller" <davem@davemloft.net>,
+	Asias He <asias@redhat.com>, Jason Wang <jasowang@redhat.com>,
+	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
+	netdev@vger.kernel.org
+Subject: [PATCHv2] vhost-net: fix use-after-free in vhost_net_flush
+Message-ID: <20130625142946.GA17414@redhat.com>
+MIME-Version: 1.0
+Content-Type: text/plain; charset=us-ascii
+Content-Disposition: inline
+X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11
+Sender:	linux-kernel-owner@vger.kernel.org
+Precedence: bulk
+List-ID: <linux-kernel.vger.kernel.org>
+X-Mailing-List:	linux-kernel@vger.kernel.org
+
+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 <asias@redhat.com>
+Acked-by: Jason Wang <jasowang@redhat.com>
+Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
+
+---
+
+Please review, and queue for 3.10 and stable.
+Changes since v1:
+	- no functional change, tweaked the commit message
+
+ drivers/vhost/net.c | 9 +++++++--
+ 1 file changed, 7 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
+index 5c77d6a..534adb0 100644
+--- a/drivers/vhost/net.c
++++ b/drivers/vhost/net.c
+@@ -149,6 +149,11 @@ static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
+ {
+ 	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);
+ }
+ 
+@@ -1073,7 +1078,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
+ 	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);
+@@ -1091,7 +1096,7 @@ err_used:
+ 	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:
+