CVE-2026-89871

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

media: video-i2c: fix kthread error pointer left in kthread_vid_cap on failure

kthread_run() returns an ERR_PTR on failure, not NULL.
When start_streaming() fails, data->kthread_vid_cap is left holding
this error pointer instead of being cleared.

This causes two subsequent bugs:
1. A future call to start_streaming() sees a non-NULL kthread_vid_cap
   and returns 0 (success) immediately, without actually starting the
   capture thread.
2. A call to stop_streaming() checks 'kthread_vid_cap == NULL' which
   is false for an error pointer, and proceeds to call kthread_stop()
   on the error pointer, leading to a kernel crash.

Fix this by resetting kthread_vid_cap to NULL on failure before
jumping to the error path.