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 <m...@redhat.com> --- I sent the same patch against 3.10 separately. This one is for stable, against 3.9/3.8 - the code moved around since then. Not sending to stable directly since Dave Miller handles it for net drivers normally. drivers/vhost/net.c | 4 ++-- drivers/vhost/vhost.c | 5 +++++ drivers/vhost/vhost.h | 1 + 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index ec6fb3f..e5ff7a5 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -856,7 +856,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd) mutex_unlock(&vq->mutex); if (oldubufs) { - vhost_ubuf_put_and_wait(oldubufs); + vhost_ubuf_put_wait_and_free(oldubufs); mutex_lock(&vq->mutex); vhost_zerocopy_signal_used(n, vq); mutex_unlock(&vq->mutex); @@ -874,7 +874,7 @@ err_used: rcu_assign_pointer(vq->private_data, oldsock); vhost_net_enable_vq(n, vq); if (ubufs) - vhost_ubuf_put_and_wait(ubufs); + vhost_ubuf_put_wait_and_free(ubufs); err_ubufs: fput(sock->file); err_vq: diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 9759249..c01d22f 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1581,5 +1581,10 @@ void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs) { kref_put(&ubufs->kref, vhost_zerocopy_done_signal); wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount)); +} + +void vhost_ubuf_put_wait_and_free(struct vhost_ubuf_ref *ubufs) +{ + vhost_ubuf_put_and_wait(ubufs); kfree(ubufs); } diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 17261e2..b53cb28 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -63,6 +63,7 @@ struct vhost_ubuf_ref { struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy); void vhost_ubuf_put(struct vhost_ubuf_ref *); void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *); +void vhost_ubuf_put_wait_and_free(struct vhost_ubuf_ref *); struct ubuf_info; -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization