From 0d05984674d7055031e4591f9bc3e74dfd7126d0 Mon Sep 17 00:00:00 2001
From: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Date: Wed, 3 May 2023 16:17:06 +0530
Subject: [PATCH] api: cgroup_get_current_controller_path: fix a segfault

cgroup_get_current_controller_path(pid, controller, current_path), the
third argument isn't currently validated and will cause segfault if the
user passes NULL, in place of expect char **.  Introduce a check to
validate current_path argument too.

Reproducer:
___________
 #include <stdio.h>
 #include <stdlib.h>
 #include <libcgroup.h>

 int main(int argc, char **argv)
 {
 	pid_t pid;
 	int ret;

 	ret = cgroup_init();
 	if (ret) {
 		printf("cgroup initialization failed:%s\n", cgroup_strerror(ret));
 		return ret;
 	}

	ret = cgroup_get_current_controller_path(atoi(argv[1]), NULL, NULL);
	/* should not reach here */
	return 0;
 }

 # gcc -o rep rep.c
 # ./rep <valid pid>
 Segmentation fault (core dumped)

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
---
 src/api.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/api.c b/src/api.c
index 99ca01b8..9b830720 100644
--- a/src/api.c
+++ b/src/api.c
@@ -4816,6 +4816,9 @@ int cgroup_get_current_controller_path(pid_t pid, const char *controller, char *
 		return ECGROUPNOTINITIALIZED;
 	}
 
+	if (!current_path)
+		return ECGOTHER;
+
 	mode = cgroup_setup_mode();
 	if (mode == CGROUP_MODE_LEGACY && !controller)
 		return ECGOTHER;
-- 
2.47.2