virtio-net: fix map leaking on error during receive

Commit bedd7e93d0196 ("virtio-net: fix use after unmap/free for sg")
tries to fix the use after free of the sg by caching the virtqueue
elements in an array and unmap them at once after receiving the
packets, But it forgot to unmap the cached elements on error which
will lead to leaking of mapping and other unexpected results.

Fixing this by detaching the cached elements on error. This addresses
CVE-2022-26353.

Reported-by: Victor Tom <vv474172261@gmail.com>
Cc: qemu-stable@nongnu.org
Fixes: CVE-2022-26353
Fixes: bedd7e93d0196 ("virtio-net: fix use after unmap/free for sg")
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index b02a0632df3f178a7df086980369e15c64530ddd..20875162531d11b10efeab75dcc5b56694976d0b 100644 (file)
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1870,6 +1870,7 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
 
 err:
     for (j = 0; j < i; j++) {
+        virtqueue_detach_element(q->rx_vq, elems[j], lens[j]);
         g_free(elems[j]);
     }