If the mbuf pointer passed to mac_mbuf_to_label() is NULL, or the tag

lookup for the label tag fails, return NULL rather than something close
to NULL.  This scenario occurs if mbuf header labeling is optional and
a policy requiring labeling is loaded, resulting in some mbufs having
labels and others not.  Previously, 0x14 would be returned because the
NULL from m_tag_find() was not treated specially.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, McAfee Research

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/security/mac/mac_net.c b/sys/security/mac/mac_net.c
index a5fc29b..51e6251 100644
--- a/sys/security/mac/mac_net.c
+++ b/sys/security/mac/mac_net.c
@@ -89,9 +89,12 @@ mac_mbuf_to_label(struct mbuf *mbuf)
 	struct m_tag *tag;
 	struct label *label;
 
+	if (mbuf == NULL)
+		return (NULL);
 	tag = m_tag_find(mbuf, PACKET_TAG_MACLABEL, NULL);
+	if (tag == NULL)
+		return (NULL);
 	label = (struct label *)(tag+1);
-
 	return (label);
 }