AppArmor: Add mising end of structure test to caps unpacking

The unpacking of struct capsx is missing a check for the end of the
caps structure.  This can lead to unpack failures depending on what else
is packed into the policy file being unpacked.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>

security/apparmor/policy_unpack.c

@@ -554,6 +554,8 @@ static struct aa_profile *unpack_profile(struct aa_ext *e)
 			goto fail;
 		if (!unpack_u32(e, &(profile->caps.extended.cap[1]), NULL))
 			goto fail;
+		if (!unpack_nameX(e, AA_STRUCTEND, NULL))
+			goto fail;
 	}
 
 	if (!unpack_rlimits(e, profile))