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Tsirkin" Cc: Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, Jia Jia Subject: [PATCH v4] virtio: rtc: tear down old virtqueues before restore Date: Thu, 7 May 2026 20:08:01 +0800 Message-Id: <20260507120801.3677552-1-physicalmtea@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit virtio_device_restore() resets the device and restores the negotiated features before calling ->restore(). viortc_freeze() intentionally leaves the existing virtqueues in place so the alarm queue can still wake the system, but viortc_restore() immediately calls viortc_init_vqs() without first deleting those old queues. If virtqueue reinitialization fails on virtio-pci, the transport error path can run vp_del_vqs() against a newly allocated vp_dev->vqs array while vdev->vqs still contains the old virtqueues. vp_del_vqs() then looks up queue state through the new array and can dereference a NULL info pointer in vp_del_vq(), crashing the guest kernel during restore. This can also happen during a non-faulty reinitialization, when one of the vp_find_vqs_msix() attempts is unsuccessful before a later attempt would succeed. Delete the stale virtqueues before rebuilding them. If restore fails before virtio_device_ready(), reuse the remove path to stop the device. Once the device is ready, return errors directly instead of deleting the virtqueues again. Fixes: 0623c7592768 ("virtio_rtc: Add module and driver core") Signed-off-by: Jia Jia Reviewed-by: Peter Hilber --- Thanks Michael for the pointer. Resending this as a new thread. drivers/virtio/virtio_rtc_driver.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/drivers/virtio/virtio_rtc_driver.c b/drivers/virtio/virtio_rtc_driver.c index a57d5e06e..4419735b0 100644 --- a/drivers/virtio/virtio_rtc_driver.c +++ b/drivers/virtio/virtio_rtc_driver.c @@ -1257,6 +1257,15 @@ static int viortc_init_vqs(struct viortc_dev *viortc) return 0; } +static void __viortc_remove(struct viortc_dev *viortc) +{ + struct virtio_device *vdev = viortc->vdev; + + viortc_clocks_deinit(viortc); + virtio_reset_device(vdev); + vdev->config->del_vqs(vdev); +} + /** * viortc_probe() - probe a virtio_rtc virtio device * @vdev: virtio device @@ -1282,7 +1291,7 @@ static int viortc_probe(struct virtio_device *vdev) ret = viortc_init_vqs(viortc); if (ret) - return ret; + goto err_reset_vdev; virtio_device_ready(vdev); @@ -1329,10 +1338,7 @@ static void viortc_remove(struct virtio_device *vdev) { struct viortc_dev *viortc = vdev->priv; - viortc_clocks_deinit(viortc); - - virtio_reset_device(vdev); - vdev->config->del_vqs(vdev); + __viortc_remove(viortc); } static int viortc_freeze(struct virtio_device *dev) @@ -1353,9 +1359,11 @@ static int viortc_restore(struct virtio_device *dev) bool notify = false; int ret; + dev->config->del_vqs(dev); + ret = viortc_init_vqs(viortc); if (ret) - return ret; + goto err_remove; alarm_viortc_vq = &viortc->vqs[VIORTC_ALARMQ]; alarm_vq = alarm_viortc_vq->vq; @@ -1364,7 +1372,7 @@ static int viortc_restore(struct virtio_device *dev) ret = viortc_populate_vq(viortc, alarm_viortc_vq, VIORTC_ALARMQ_BUF_CAP, false); if (ret) - return ret; + goto err_remove; notify = virtqueue_kick_prepare(alarm_vq); } @@ -1372,8 +1380,12 @@ static int viortc_restore(struct virtio_device *dev) virtio_device_ready(dev); if (notify && !virtqueue_notify(alarm_vq)) - ret = -EIO; + return -EIO; + + return 0; +err_remove: + __viortc_remove(viortc); return ret; } -- 2.34.1