firewall3: fix process termination in child processes

When execv() or execl() fail in child processes, the child would
continue executing parent code instead of properly terminating.
This could lead to unexpected behavior with multiple firewall3
processes running.

Add proper error handling and _exit(EXIT_FAILURE) calls after failed
exec operations in __fw3_command_pipe() and fw3_hotplug() to ensure
child processes terminate immediately on exec failure.

Signed-off-by: Stacy Corcoran <stacy.corcoran@verkada.com>

Author: stacycorcoran

utils.c

@@ -271,6 +271,10 @@ __fw3_command_pipe(bool silent, const char *command, ...)
 
 		execv(command, args);
 
+		/* Only reach on execv failure - must exit to prevent child continuing */
+		warn("Unable to execute %s: %s", command, strerror(errno));
+		_exit(1);
+
 	default:
 		signal(SIGPIPE, SIG_IGN);
 		pipe_pid = pid;
@@ -771,7 +775,7 @@ fw3_hotplug(bool add, void *zone, void *device)
 	switch (fork())
 	{
 	case -1:
-		warn("Unable to fork(): %s\n", strerror(errno));
+		warn("Unable to fork(): %s", strerror(errno));
 		return false;
 
 	case 0:
@@ -794,8 +798,8 @@ fw3_hotplug(bool add, void *zone, void *device)
 
 	execl(FW3_HOTPLUG, FW3_HOTPLUG, "firewall", NULL);
 
-	/* unreached */
-	return false;
+	/* Only reach on execl() failure - must exit to prevent child continuing */
+	_exit(1);
 }
 
 int