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[82.192.137.139]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4976bd52f3fsm36693245e9.0.2026.07.29.07.44.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2026 07:44:30 -0700 (PDT) Date: Wed, 29 Jul 2026 16:44:23 +0200 From: Stefano Garzarella To: Weiming Shi Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Stefan Hajnoczi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , virtualization@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xiang Mei , stable@vger.kernel.org Subject: Re: [PATCH] vsock/virtio: prevent workers from using deleted virtqueues Message-ID: References: <20260727035804.1860862-1-bestswngs@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260727035804.1860862-1-bestswngs@gmail.com> On Sun, Jul 26, 2026 at 08:58:01PM -0700, Weiming Shi wrote: >The RX, TX and event workers read their virtqueue pointers before taking >the mutex that protects the queue and its run flag. A work item delayed >across freeze and restore can therefore retain a pointer deleted by >virtio_vsock_vqs_del(), observe the run flag for the replacement queues, >and use the freed pointer. > >RX has an additional path: when rx_run is clear, the common exit still >refills the RX queue. A queued worker can consequently call >virtqueue_add_sgs() immediately after freeze deletes the virtqueues. > >BUG: KASAN: slab-use-after-free in virtqueue_add_sgs >Read of size 4 by task kworker/2:1 >Workqueue: virtio_vsock virtio_transport_rx_work >Call Trace: > virtqueue_add_sgs (drivers/virtio/virtio_ring.c:2796) > virtio_vsock_rx_fill (net/vmw_vsock/virtio_transport.c:332) > virtio_transport_rx_work (net/vmw_vsock/virtio_transport.c:701) > process_one_work (kernel/workqueue.c:3314) > worker_thread (kernel/workqueue.c:3478) > kthread (kernel/kthread.c:436) > ret_from_fork (arch/x86/kernel/process.c:158) > ret_from_fork_asm (arch/x86/entry/entry_64.S:245) >... >Freed by task 141: > kfree (mm/slub.c:6566) > vp_del_vq (drivers/virtio/virtio_pci_common.c:259) > vp_del_vqs (drivers/virtio/virtio_pci_common.c:285) > virtio_vsock_freeze (net/vmw_vsock/virtio_transport.c:912) > virtio_device_freeze (drivers/virtio/virtio.c:658) > virtio_pci_freeze (drivers/virtio/virtio_pci_common.c:601) > pci_pm_freeze (drivers/pci/pci-driver.c:1098) > device_suspend (drivers/base/power/main.c:1968) >Kernel panic - not syncing: KASAN: panic_on_warn set ... > >Read each worker's virtqueue under its mutex after confirming that the >queue is running, and only refill RX while RX is running. > >Fixes: b917507e5ad9 ("vsock/virtio: stop workers during the .remove()") >Cc: stable@vger.kernel.org >Reported-by: Xiang Mei >Assisted-by: OpenAI-Codex:gpt-5 >Signed-off-by: Weiming Shi >--- > net/vmw_vsock/virtio_transport.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > >diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >index 57f2d6ec3ffc..79cf19f58943 100644 >--- a/net/vmw_vsock/virtio_transport.c >+++ b/net/vmw_vsock/virtio_transport.c >@@ -346,12 +346,13 @@ static void virtio_transport_tx_work(struct work_struct *work) > struct virtqueue *vq; > bool added = false; > >- vq = vsock->vqs[VSOCK_VQ_TX]; > mutex_lock(&vsock->tx_lock); > > if (!vsock->tx_run) > goto out; > >+ vq = vsock->vqs[VSOCK_VQ_TX]; >+ > do { > struct sk_buff *skb; > unsigned int len; >@@ -451,13 +452,13 @@ static void virtio_transport_event_work(struct work_struct *work) > container_of(work, struct virtio_vsock, event_work); > struct virtqueue *vq; > >- vq = vsock->vqs[VSOCK_VQ_EVENT]; >- > mutex_lock(&vsock->event_lock); > > if (!vsock->event_run) > goto out; > >+ vq = vsock->vqs[VSOCK_VQ_EVENT]; >+ > do { > struct virtio_vsock_event *event; > unsigned int len; >@@ -634,13 +635,13 @@ static void virtio_transport_rx_work(struct work_struct *work) > container_of(work, struct virtio_vsock, rx_work); > struct virtqueue *vq; > >- vq = vsock->vqs[VSOCK_VQ_RX]; >- > mutex_lock(&vsock->rx_lock); > > if (!vsock->rx_run) > goto out; > >+ vq = vsock->vqs[VSOCK_VQ_RX]; >+ > do { > virtqueue_disable_cb(vq); > for (;;) { >@@ -689,7 +690,8 @@ static void virtio_transport_rx_work(struct work_struct *work) > } while (!virtqueue_enable_cb(vq)); > > out: >- if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2) >+ if (vsock->rx_run && Instead of adding this check, what about adding a new label... >+ vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2) > virtio_vsock_rx_fill(vsock); out_nofill: > mutex_unlock(&vsock->rx_lock); And use it when we check `vsock->rx_run` ? Since we are taking the mutex, we don't need to check it again. The rest LGTM, but I agree with Bobby about the split, since the Fixes tag here is confusing. I'll reply there. Thanks, Stefano