prune_init_cgroup: don't dereference NULL

This is to avoid:

https://errors.ubuntu.com/problem/d640a68bf7343705899d7ca8c6bc070d477cd845

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index b1c764f2b7083ed4c542b22e56721e93f7ab4f1e..0f7a2ac16cba2b97cee0ea5679d10e230e6df658 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -198,7 +198,12 @@ cgroup_driver_t cgroup_driver(void)
 #define INIT_SCOPE "/init.scope"
 void prune_init_scope(char *cg)
 {
-       char *point = cg + strlen(cg) - strlen(INIT_SCOPE);
+       char *point;
+
+       if (!cg)
+               return;
+
+       point = cg + strlen(cg) - strlen(INIT_SCOPE);
        if (point < cg)
                return;
        if (strcmp(point, INIT_SCOPE) == 0) {