From: Aleksandr Nogikh <nogikh@google.com> stable inclusion from stable-v6.6.143 commit 2b32b2fb241435145ea199efac024540759d2495 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9495 Reference: https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/... ------------------------------------------------- [ Upstream commit 90918794a4e2c3b440f8fcf3847765a8b1d81b25 ] 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. Fixes: 39efa3ef3a37 ("signal: Use GROUP_STOP_PENDING to stop once for a single group stop") Assisted-by: Gemini:gemini-3.1-pro-preview Gemini:gemini-3-flash-preview syzbot Reported-by: syzbot+b109633ea805cac54a61@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b109633ea805cac54a61 Link: https://syzkaller.appspot.com/ai_job?id=d70208cc-862b-4fe3-bf02-3031e10cd0b3 Signed-off-by: Aleksandr Nogikh <nogikh@google.com> Link: https://patch.msgid.link/20260521142240.2973022-1-nogikh@google.com Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Chen Jinghuang <chenjinghuang2@huawei.com> --- kernel/signal.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/signal.c b/kernel/signal.c index 50aa72d6ff4e..91019f737a94 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1385,6 +1385,7 @@ int zap_other_threads(struct task_struct *p) int count = 0; p->signal->group_stop_count = 0; + task_clear_jobctl_pending(p, JOBCTL_PENDING_MASK); while_each_thread(p, t) { task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); -- 2.34.1