CVE-2026-68217 media: pwc: Drain fill_buf on start_streaming() failure
A race condition in the Linux kernel pwc driver leaks a buffer on streaming failure, potentially causing a kernel warning and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68217?
CVE-2026-68217 is a memory corruption vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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/
Which versions are affected by CVE-2026-68217?
How do I fix CVE-2026-68217?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-68217 being exploited?
There is no known exploitation of CVE-2026-68217 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68217, DEBIAN-CVE-2026-68217, GHSA-mj4m-5r47-3f8j, UBUNTU-CVE-2026-68217.