selinux: fix GPF on invalid policy

levdatum->level can be NULL if we encounter an error while loading
the policy during sens_read prior to initializing it.  Make sure
sens_destroy handles that case correctly.

Reported-by: syzbot+6664500f0f18f07a5c0e@syzkaller.appspotmail.com
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index a50d625e7946..c1c31e33657a 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -732,7 +732,8 @@ static int sens_destroy(void *key, void *datum, void *p)
         kfree(key);
         if (datum) {
                 levdatum = datum;
-                ebitmap_destroy(&levdatum->level->cat);
+                if (levdatum->level)
+                        ebitmap_destroy(&levdatum->level->cat);
                 kfree(levdatum->level);
         }
         kfree(datum);