wrapper: fix segfault in cgroup_add_controller()

The second argument passed to cgroup_add_controller() is of type
char * and the user might pass NULL in place of the arguments, causing
a segfault.  segfault is trigger when the NULL, argument values is used
without checks, fix it by checking for NULL before proceeding.

Reproducer:
-----------

int main(void)
{
	struct cgroup_controller *cgc;
	struct cgroup *cgrp;
	int ret;

	cgroup_init();
	if (ret)
		exit(1);

	cgrp = cgroup_new_cgroup("fuzzer");
	if (!cgrp)
		exit(1);

	cgc = cgroup_add_controller(cgrp, "cpu");
	if (!cgc)
		exit(1);

	cgroup_add_controller(cgrp, NULL);

	// should not reach here
	return 0;
}

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
(cherry picked from commit 42436e7e32412c32d2130198fe8a4c0ff48e1d07)

diff --git a/src/wrapper.c b/src/wrapper.c
index c97b529ea5fabbc2446c1aaed4f0596484e45fd2..2038ae787dfdcea2f3f4d5097916d3a7b0a8b3a8 100644 (file)
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -63,7 +63,7 @@ struct cgroup_controller *cgroup_add_controller(struct cgroup *cgroup, const cha
        struct cgroup_controller *controller;
        int i, ret;
 
-       if (!cgroup)
+       if (!cgroup || !name)
                return NULL;
 
        /* Still not sure how to handle the failure here. */