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>

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index a50d625e7946f1803bf5e8c7a9f02b734fe46bc9..c1c31e33657ae6d6b9f6247a4c7ac29f6026bc4d 100644 (file)
--- 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);