CVE-2026-68217

In the Linux kernel, the following vulnerability has been resolved:

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/