Re: [PATCH net] vhost-net: fix use-after-free in vhost_net_flush
From: Asias He <hidden>
Date: 2013-06-21 07:21:12
Also in:
kvm, lkml, virtualization
On Thu, Jun 20, 2013 at 02:48:13PM +0300, Michael S. Tsirkin wrote:
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 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. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Asias He <redacted>
quoted hunk ↗ jump to hunk
--- Dave, this is needed for stable as well, but the code has moved a bit since then. I'll post a patch tweaked to apply against 3.9 and 3.8 separately. 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:-- MST
-- Asias