From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH net] vhost-vsock: fix use after free Date: Thu, 27 Sep 2018 16:43:01 +0800 Message-ID: <20180927084301.573-1-jasowang__35068.374584853$1538037683$gmane$org@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: stefanha@redhat.com, mst@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org The access of vsock is not protected by vhost_vsock_lock. This may lead use after free since vhost_vsock_dev_release() may free the pointer at the same time. Fix this by holding the lock during the acess. Reported-by: syzbot+e3e074963495f92a89ed@syzkaller.appspotmail.com Fixes: 16320f363ae1 ("vhost-vsock: add pkt cancel capability") Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Cc: Stefan Hajnoczi Signed-off-by: Jason Wang --- - The patch is needed for -stable. --- drivers/vhost/vsock.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index 34bc3ab40c6d..7d0b292867fd 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -210,21 +210,27 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt) struct vhost_vsock *vsock; int len = pkt->len; + spin_lock_bh(&vhost_vsock_lock); + /* Find the vhost_vsock according to guest context id */ - vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid)); + vsock = __vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid)); if (!vsock) { virtio_transport_free_pkt(pkt); + spin_unlock_bh(&vhost_vsock_lock); return -ENODEV; } if (pkt->reply) atomic_inc(&vsock->queued_replies); - spin_lock_bh(&vsock->send_pkt_list_lock); + spin_lock(&vsock->send_pkt_list_lock); list_add_tail(&pkt->list, &vsock->send_pkt_list); - spin_unlock_bh(&vsock->send_pkt_list_lock); + spin_unlock(&vsock->send_pkt_list_lock); vhost_work_queue(&vsock->dev, &vsock->send_pkt_work); + + spin_unlock_bh(&vhost_vsock_lock); + return len; } @@ -236,18 +242,22 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk) int cnt = 0; LIST_HEAD(freeme); + spin_lock_bh(&vhost_vsock_lock); + /* Find the vhost_vsock according to guest context id */ - vsock = vhost_vsock_get(vsk->remote_addr.svm_cid); - if (!vsock) + vsock = __vhost_vsock_get(vsk->remote_addr.svm_cid); + if (!vsock) { + spin_unlock_bh(&vhost_vsock_lock); return -ENODEV; + } - spin_lock_bh(&vsock->send_pkt_list_lock); + spin_lock(&vsock->send_pkt_list_lock); list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) { if (pkt->vsk != vsk) continue; list_move(&pkt->list, &freeme); } - spin_unlock_bh(&vsock->send_pkt_list_lock); + spin_unlock(&vsock->send_pkt_list_lock); list_for_each_entry_safe(pkt, n, &freeme, list) { if (pkt->reply) @@ -265,6 +275,8 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk) vhost_poll_queue(&tx_vq->poll); } + spin_unlock_bh(&vhost_vsock_lock); + return 0; } -- 2.17.1