CVE-2026-89749

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

tracing: Fix crash passing ERR PTR to kthread stop()

event test stuff() calls kthread run() and unconditionally passes the returned task struct pointer to kthread stop(). kthread run() returns an error pointer such as ERR PTR(-ENOMEM) when kthread creation fails, for example under memory pressure during the boot-time event self-test. kthread stop() then dereferences the invalid pointer, crashing the kernel.

Check the result of kthread run() before passing it to kthread stop(). Use WARN ON() so that a failure to create the self-test thread does not go unnoticed, matching the ring-buffer self-test fix in commit 91542863abad ("ring-buffer: Fix crash passing ERR PTR to kthread stop()").