CVE-2024-26686

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

fs/proc: dotaskstat: use sig->stats_lock to gather the threads/children stats

locktasksighand() can trigger a hard lockup. If NRCPUS threads call dotaskstat() at the same time and the process has NRTHREADS, it will spin with irqs disabled O(NRCPUS * NRTHREADS) time.

Change dotaskstat() to use sig->stats_lock to gather the statistics outside of ->siglock protected section, in the likely case this code will run lockless.