selinux: add the processing of the failure of avc_add_xperms_decision()

When avc_add_xperms_decision() fails, the information recorded by the new
avc node is incomplete. In this case, the new avc node should be released
instead of replacing the old avc node.

Cc: stable@vger.kernel.org
Fixes: fa1aa14 ("selinux: extended permissions for ioctls")
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: Zhen Lei

security/selinux/avc.c

@@ -907,7 +907,11 @@ static int avc_update_node(u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
 		node->ae.avd.auditdeny &= ~perms;
 		break;
 	case AVC_CALLBACK_ADD_XPERMS:
-		avc_add_xperms_decision(node, xpd);
+		rc = avc_add_xperms_decision(node, xpd);
+		if (rc) {
+			avc_node_kill(node);
+			goto out_unlock;
+		}
 		break;
 	}
 	avc_node_replace(node, orig);