coredump: set ->group_exit_code for other CLONE_VM tasks too

User visible change.

do_coredump() kills all threads which share the same ->mm but only the
coredumping process gets the proper exit_code.  Other tasks which share
the same ->mm die "silently" and return status == 0 to parent.

This is historical behaviour, not actually a bug.  But I think Frank
Heckenbach rightly dislikes the current behaviour.  Simple test-case:

	#include <stdio.h>
	#include <unistd.h>
	#include <signal.h>
	#include <sys/wait.h>

	int main(void)
	{
		int stat;

		if (!fork()) {
			if (!vfork())
				kill(getpid(), SIGQUIT);
		}

		wait(&stat);
		printf("stat=%x\n", stat);
		return 0;
	}

Before this patch it prints "stat=0" despite the fact the child was killed
by SIGQUIT.  After this patch the output is "stat=3" which obviously makes
more sense.

Even with this patch, only the task which originates the coredumping gets
"|= 0x80" if the core was actually dumped, but at least the coredumping
signal is visible to do_wait/etc.

Reported-by: Frank Heckenbach <f.heckenbach@fh-soft.de>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 89d4080c1435..829a6c6d1803 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1561,12 +1561,13 @@ out:
         return ispipe;
 }
 
-static int zap_process(struct task_struct *start)
+static int zap_process(struct task_struct *start, int exit_code)
 {
         struct task_struct *t;
         int nr = 0;
 
         start->signal->flags = SIGNAL_GROUP_EXIT;
+        start->signal->group_exit_code = exit_code;
         start->signal->group_stop_count = 0;
 
         t = start;
@@ -1591,8 +1592,7 @@ static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
         spin_lock_irq(&tsk->sighand->siglock);
         if (!signal_group_exit(tsk->signal)) {
                 mm->core_state = core_state;
-                tsk->signal->group_exit_code = exit_code;
-                nr = zap_process(tsk);
+                nr = zap_process(tsk, exit_code);
         }
         spin_unlock_irq(&tsk->sighand->siglock);
         if (unlikely(nr < 0))
@@ -1641,7 +1641,7 @@ static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
                         if (p->mm) {
                                 if (unlikely(p->mm == mm)) {
                                         lock_task_sighand(p, &flags);
-                                        nr += zap_process(p);
+                                        nr += zap_process(p, exit_code);
                                         unlock_task_sighand(p, &flags);
                                 }
                                 break;