From: Valery Borovsky Date: Wed, 13 May 2026 05:42:44 +0000 (+0300) Subject: media: pwc: Drain fill_buf on start_streaming() failure X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=906e410dcffbbd99fb4081abab817a830033aa28;p=thirdparty%2Fkernel%2Flinux.git media: pwc: Drain fill_buf on start_streaming() failure pwc_isoc_init() submits its isochronous URBs with usb_submit_urb(.., GFP_KERNEL) in a loop. After the first URB is submitted, its completion handler pwc_isoc_handler() can run on another CPU before the loop finishes: start_streaming() pwc_isoc_init() usb_submit_urb(urbs[0], GFP_KERNEL) pwc_isoc_handler(urbs[0]) pdev->fill_buf = pwc_get_next_fill_buf(pdev) usb_submit_urb(urbs[i>0], ..) -> fails pwc_isoc_cleanup(pdev) /* kills URBs */ return ret; pwc_cleanup_queued_bufs(pdev, VB2_BUF_STATE_QUEUED) pwc_get_next_fill_buf() detaches a buffer from pdev->queued_bufs and stores it in pdev->fill_buf. The error path in start_streaming() only drains pdev->queued_bufs, so the buffer parked in pdev->fill_buf is leaked. vb2_start_streaming() then triggers WARN_ON(owned_by_drv_count). stop_streaming() already handles this since commit 80b0963e1698 ("[media] pwc: fix WARN_ON"), which added the fill_buf drain in the teardown path but not in the start_streaming() error path. Mirror that handling on failure so start_streaming() returns with no buffer owned by the driver. Issue identified by automated review of the INV-003 series at https://sashiko.dev/ Fixes: 885fe18f5542 ("[media] pwc: Replace private buffer management code with videobuf2") Cc: stable@vger.kernel.org Signed-off-by: Valery Borovsky Signed-off-by: Hans Verkuil --- diff --git a/drivers/media/usb/pwc/pwc-if.c b/drivers/media/usb/pwc/pwc-if.c index 59b99ac8fcb6..e2884b04d952 100644 --- a/drivers/media/usb/pwc/pwc-if.c +++ b/drivers/media/usb/pwc/pwc-if.c @@ -730,6 +730,11 @@ static int start_streaming(struct vb2_queue *vq, unsigned int count) pwc_camera_power(pdev, 0); /* And cleanup any queued bufs!! */ pwc_cleanup_queued_bufs(pdev, VB2_BUF_STATE_QUEUED); + if (pdev->fill_buf) { + vb2_buffer_done(&pdev->fill_buf->vb.vb2_buf, + VB2_BUF_STATE_QUEUED); + pdev->fill_buf = NULL; + } } mutex_unlock(&pdev->v4l2_lock);