CVE-2026-53352

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

signal: clear JOBCTL_PENDING_MASK for caller in zap_other_threads()

When a multi-threaded process receives a stop signal (e.g., SIGSTOP),

do_signal_stop() sets JOBCTL_STOP_PENDING and JOBCTL_STOP_CONSUME on all

threads and sets signal->group_stop_count to the number of threads. If

one of the threads concurrently calls execve(), de_thread() invokes

zap_other_threads() to kill all other threads. zap_other_threads()

aborts the pending group stop by resetting signal->group_stop_count to 0

and clears the JOBCTL_PENDING_MASK for all other threads. However, it

fails to clear the job control flags for the calling thread.

When execve() completes, the calling thread returns to user mode and

checks for pending signals. Seeing the stale JOBCTL_STOP_PENDING flag,

it calls do_signal_stop(), which invokes task_participate_group_stop().

Since JOBCTL_STOP_CONSUME is still set, it attempts to decrement the

already-zero signal->group_stop_count, triggering a warning:

sig->group_stop_count == 0

WARNING: CPU: 1 PID: 6475 at kernel/signal.c:373

task_participate_group_stop+0x215/0x2d0

Call Trace:

<TASK>

do_signal_stop+0x3be/0x5c0 kernel/signal.c:2619

get_signal+0xa8c/0x1330 kernel/signal.c:2884

arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337

exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98

do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100

entry_SYSCALL_64_after_hwframe+0x77/0x7f

</TASK>

Fix this race condition by clearing the JOBCTL_PENDING_MASK for the

calling thread in zap_other_threads(), ensuring it does not retain any

stale job control state after the thread group is destroyed. This aligns

with other functions that tear down a thread group and abort group

stops, such as zap_process() and complete_signal(), which correctly

clear these flags for all threads including the current one.