[PATCH 3.18 29/52] selinux: fix GPF on invalid policy

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stephen Smalley <sds@xxxxxxxxxxxxx>

commit 5b0e7310a2a33c06edc7eb81ffc521af9b2c5610 upstream.

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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 security/selinux/ss/policydb.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -717,7 +717,8 @@ static int sens_destroy(void *key, void
 	kfree(key);
 	if (datum) {
 		levdatum = datum;
-		ebitmap_destroy(&levdatum->level->cat);
+		if (levdatum->level)
+			ebitmap_destroy(&levdatum->level->cat);
 		kfree(levdatum->level);
 	}
 	kfree(datum);