On 06/20/2013 07:48 PM, 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@xxxxxxxxxx> > --- > > 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: Acked-by: Jason Wang <jasowang@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html