Linux Kernel CVE-2025-39976

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

futex: Use correct exit on failure from futex_hash_allocate_default()

copy_process() uses the wrong error exit path from futex_hash_allocate_default(). After exiting from futex_hash_allocate_default(), neither tasklist_lock nor siglock has been acquired. The exit label bad_fork_core_free unlocks both of these locks which is wrong.

The next exit label, bad_fork_cancel_cgroup, is the correct exit. sched_cgroup_fork() did not allocate any resources that need to freed.

Use bad_fork_cancel_cgroup on error exit from futex_hash_allocate_default().

The affected product is the mainline and stable Linux kernel, specifically builds that include the default futex hash allocation in copy_process() prior to the fix commits. No CPE strings were provided in the intelligence, so exact version ranges are not enumerated in the input; the fix is tracked in the kernel stable tree via commits at https://git.kernel.org/stable/c/4ec3c15462b9f44562f45723a92e2807746ba7d1 and https://git.kernel.org/stable/c/f1635765cd0fdbf27b04d9a50be91a01b5adda13. Distributions rebasing on the affected stable branches (and their downstream kernels) are impacted until they pick up these commits.