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authorMichael S. Tsirkin <mst@redhat.com>2013-06-25 18:29:46 +0400
committerMichael S. Tsirkin <mst@redhat.com>2013-07-07 15:06:22 +0400
commitc38e39c378f46f00ce922dd40a91043a9925c28d (patch)
treea5286110beeea3f5fef0c86fb44535d91402ea3b /drivers/vhost
parent8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (diff)
downloadlinux-c38e39c378f46f00ce922dd40a91043a9925c28d.tar.xz
vhost-net: fix use-after-free in vhost_net_flush
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>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/net.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f80d3dd41d8c..8ca5ac71b845 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -150,6 +150,11 @@ 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);
}
@@ -948,7 +953,7 @@ 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);
@@ -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: