From d80f7d7b2c75c5954d335dffbccca62a5002c3e0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 21 Jun 2022 14:38:52 -0500 Subject: signal: Guarantee that SIGNAL_GROUP_EXIT is set on process exit Track how many threads have not started exiting and when the last thread starts exiting set SIGNAL_GROUP_EXIT. This guarantees that SIGNAL_GROUP_EXIT will get set when a process exits. In practice this achieves nothing as glibc's implementation of _exit calls sys_group_exit then sys_exit. While glibc's implemenation of pthread_exit calls exit (which cleansup and calls _exit) if it is the last thread and sys_exit if it is the last thread. This means the only way the kernel might observe a process that does not set call exit_group is if the language runtime does not use glibc. With more cleanups I hope to move the decrement of quick_threads earlier. Link: https://lkml.kernel.org/r/87bkukd4tc.fsf_-_@email.froward.int.ebiederm.org Signed-off-by: "Eric W. Biederman" --- kernel/exit.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index a3929e5e6d61..d8ecbaa514f7 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -733,11 +733,29 @@ static void check_stack_usage(void) static inline void check_stack_usage(void) {} #endif +static void synchronize_group_exit(struct task_struct *tsk, long code) +{ + struct sighand_struct *sighand = tsk->sighand; + struct signal_struct *signal = tsk->signal; + + spin_lock_irq(&sighand->siglock); + signal->quick_threads--; + if ((signal->quick_threads == 0) && + !(signal->flags & SIGNAL_GROUP_EXIT)) { + signal->flags = SIGNAL_GROUP_EXIT; + signal->group_exit_code = code; + signal->group_stop_count = 0; + } + spin_unlock_irq(&sighand->siglock); +} + void __noreturn do_exit(long code) { struct task_struct *tsk = current; int group_dead; + synchronize_group_exit(tsk, code); + WARN_ON(tsk->plug); kcov_task_exit(tsk); -- cgit v1.2.3