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

A vulnerability was found in the dotaskstat function in the Linux kernel, where due to excessive lock contention, a potential hard lockup could be created. This can create a performance bottleneck and lead to kernel unresponsiveness...

CVE-2024-26686

In the Linux kernel, the following vulnerability has been resolved: fs/proc: dotaskstat: use sig-statslock 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...