selftests/landlock: Fix socket file descriptor leaks in audit helpers

audit_init() opens a netlink socket and configures it, but leaks the
file descriptor if audit_set_status() or setsockopt() fails.  Fix this
by jumping to an error path that closes the socket before returning.

Apply the same fix to audit_init_with_exe_filter(), which leaks the file
descriptor from audit_init() if audit_init_filter_exe() or
audit_filter_exe() fails, and to audit_cleanup(), which leaks it if
audit_init_filter_exe() fails in FIXTURE_TEARDOWN_PARENT().

Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b2 ("selftests/landlock: Add tests for audit flags and domain IDs")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260402192608.1458252-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Author: l0kod

tools/testing/selftests/landlock/audit.h

@@ -379,19 +379,25 @@ static int audit_init(void)
 
 	err = audit_set_status(fd, AUDIT_STATUS_ENABLED, 1);
 	if (err)
-		return err;
+		goto err_close;
 
 	err = audit_set_status(fd, AUDIT_STATUS_PID, getpid());
 	if (err)
-		return err;
+		goto err_close;
 
 	/* Sets a timeout for negative tests. */
 	err = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &audit_tv_default,
 			 sizeof(audit_tv_default));
-	if (err)
-		return -errno;
+	if (err) {
+		err = -errno;
+		goto err_close;
+	}
 
 	return fd;
+
+err_close:
+	close(fd);
+	return err;
 }
 
 static int audit_init_filter_exe(struct audit_filter *filter, const char *path)
@@ -441,8 +447,10 @@ static int audit_cleanup(int audit_fd, struct audit_filter *filter)
 
 		filter = &new_filter;
 		err = audit_init_filter_exe(filter, NULL);
-		if (err)
+		if (err) {
+			close(audit_fd);
 			return err;
+		}
 	}
 
 	/* Filters might not be in place. */
@@ -468,11 +476,15 @@ static int audit_init_with_exe_filter(struct audit_filter *filter)
 
 	err = audit_init_filter_exe(filter, NULL);
 	if (err)
-		return err;
+		goto err_close;
 
 	err = audit_filter_exe(fd, filter, AUDIT_ADD_RULE);
 	if (err)
-		return err;
+		goto err_close;
 
 	return fd;
+
+err_close:
+	close(fd);
+	return err;
 }