treewide: use _exit() over exit()

In the podman CI I noticed many seccomp denials in our logs even though
tests passed:
comm="pasta.avx2" exe="/usr/bin/pasta.avx2" sig=31 arch=c000003e
syscall=202 compat=0 ip=0x7fb3d31f69db code=0x80000000

Which is futex being called and blocked by the pasta profile. After a
few tries I managed to reproduce locally with this loop in ~20 min:
while :;
  do podman run -d --network bridge quay.io/libpod/testimage:20241011 \
	sleep 100 && \
  sleep 10 && \
  podman rm -fa -t0
done

And using a pasta version with prctl(PR_SET_DUMPABLE, 1); set I got the
following stack trace:
Stack trace of thread 1:
  #0  0x00007fc95e6de91b __lll_lock_wait_private (libc.so.6 + 0x9491b)
  #1  0x00007fc95e68d6de __run_exit_handlers (libc.so.6 + 0x436de)
  #2  0x00007fc95e68d70e exit (libc.so.6 + 0x4370e)
  #3  0x000055f31b78c50b n/a (n/a + 0x0)
  #4  0x00007fc95e68d70e exit (libc.so.6 + 0x4370e)
  #5  0x000055f31b78d5a2 n/a (n/a + 0x0)

Pasta got killed in exit(), it seems glibc is trying to use a lock when
running exit handlers even though no exit handlers are defined.

Given no exit handlers are needed we can call _exit() instead. This
skips exit handlers and does not flush stdio streams compared to exit()
which should be fine for the use here.

Based on the input from Stefano I did not change the test/doc programs
or qrap as they do not use seccomp filters.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/pasta.c b/pasta.c
index ff41c95..f15084d 100644
--- a/pasta.c
+++ b/pasta.c
@@ -73,12 +73,12 @@ void pasta_child_handler(int signal)
 	    !waitid(P_PID, pasta_child_pid, &infop, WEXITED | WNOHANG)) {
 		if (infop.si_pid == pasta_child_pid) {
 			if (infop.si_code == CLD_EXITED)
-				exit(infop.si_status);
+				_exit(infop.si_status);
 
 			/* If killed by a signal, si_status is the number.
 			 * Follow common shell convention of returning it + 128.
 			 */
-			exit(infop.si_status + 128);
+			_exit(infop.si_status + 128);
 
 			/* Nothing to do, detached PID namespace going away */
 		}
@@ -499,7 +499,7 @@ void pasta_netns_quit_inotify_handler(struct ctx *c, int inotify_fd)
 		return;
 
 	info("Namespace %s is gone, exiting", c->netns_base);
-	exit(EXIT_SUCCESS);
+	_exit(EXIT_SUCCESS);
 }
 
 /**
@@ -525,7 +525,7 @@ void pasta_netns_quit_timer_handler(struct ctx *c, union epoll_ref ref)
 			return;
 
 		info("Namespace %s is gone, exiting", c->netns_base);
-		exit(EXIT_SUCCESS);
+		_exit(EXIT_SUCCESS);
 	}
 
 	close(fd);