From: Qian Chen <cq674350...@163.com>
The OVS LLDP implementation includes support for AutoAttach standard, which
the 'upstream' lldpd project does not include. As part of adding this
support, the message parsing for these TLVs did not include proper length
checks for the LLDP_TLV_AA_ELEMENT_SUBTYPE and the
LLDP_TLV_AA_ISID_VLAN_ASGNS_SUBTYPE elements. The result is that a message
without a proper boundary will cause an over read of memory, and lead to
undefined results, including crashes or other unidentified behavior.
The fix is to introduce proper bounds checking for these elements. Introduce
a unit test to ensure that we have some proper rejection in this code
base in the future.
Fixes: be53a5c447c3 ("auto-attach: Initial support for Auto-Attach standard")
Signed-off-by: Qian Chen <cq674350...@163.com>
Co-authored-by: Aaron Conole <acon...@redhat.com>
Signed-off-by: Aaron Conole <acon...@redhat.com>
---
NOTES: This bug is publicly known and disclosed at
https://github.com/openvswitch/ovs/pull/405 which makes this mostly
a repost.
I have modified the test case to ensure that it would run
correctly when doing both 'make check-kernel' and
'make check-system-userspace'
lib/lldp/lldp.c | 2 ++
tests/system-traffic.at | 27 +++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/lib/lldp/lldp.c b/lib/lldp/lldp.c
index dfeb2a8002..6fdcfef569 100644
--- a/lib/lldp/lldp.c
+++ b/lib/lldp/lldp.c
@@ -583,6 +583,7 @@ lldp_decode(struct lldpd *cfg OVS_UNUSED, char *frame, int
s,
switch(tlv_subtype) {
case LLDP_TLV_AA_ELEMENT_SUBTYPE:
+ CHECK_TLV_SIZE(50, "ELEMENT");
PEEK_BYTES(&msg_auth_digest, sizeof msg_auth_digest);
aa_element_dword = PEEK_UINT32;
@@ -629,6 +630,7 @@ lldp_decode(struct lldpd *cfg OVS_UNUSED, char *frame, int
s,
break;
case LLDP_TLV_AA_ISID_VLAN_ASGNS_SUBTYPE:
+ CHECK_TLV_SIZE(36, "ISID_VLAN_ASGNS");
PEEK_BYTES(&msg_auth_digest, sizeof msg_auth_digest);
/* Subtract off tlv type and length (2Bytes) + OUI (3B) +
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index e5403519f2..0928bfe540 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -7440,3 +7440,30 @@ OVS_WAIT_UNTIL([cat p2.pcap | grep -E "0x0050: *0000
*0000 *5002 *2000 *b85e *00
OVS_TRAFFIC_VSWITCHD_STOP
AT_CLEANUP
+
+AT_SETUP([autoattach - malformed lldp])
+OVS_TRAFFIC_VSWITCHD_START()
+
+ADD_NAMESPACES(at_ns0)
+
+dnl Set up simple bridge port to receive lldp packets
+ADD_VETH(p0, at_ns0, br0, "172.31.1.1/24", "f6:b4:26:aa:5f:00")
+
+NETNS_DAEMONIZE([at_ns0], [tcpdump -l -n -xx -U -i p0 > p0.pcap],
[tcpdump.pid])
+sleep 1
+
+dnl Enable lldp
+AT_CHECK([ovs-vsctl set interface ovs-p0 lldp:enable=true])
+
+dnl Send a malformed lldp packet
+NS_CHECK_EXEC([at_ns0], [$PYTHON3 $srcdir/sendpkt.py p0 01 80 c2 00 00 0e f6
b4 26 aa 5f 00 88 cc 02 07 04 f6 b4 26 aa 5f 00 04 03 05 76 32 06 02 00 78 0c
50 44 45 41 44 42 45 45 46 44 45 41 44 42 45 45 46 44 45 41 44 42 45 45 46 44
45 41 44 42 45 45 46 44 45 41 44 42 45 45 46 44 45 41 44 42 45 45 46 44 45 41
44 42 45 45 46 44 45 41 44 42 45 45 46 44 45 41 44 42 45 45 46 44 45 41 44 42
45 45 46 fe 05 00 04 0d 0c 01 00 00 >/dev/null])
+
+dnl Check the expected lldp packet by looking for the end
+OVS_WAIT_UNTIL([cat p0.pcap | grep -E "0x0070: *4546 *fe05 *0004 *0d0c *0100
*00" 2>&1 1>/dev/null])
+
+AT_CHECK([grep -o "ISID_VLAN_ASGNS TLV too short" ovs-vswitchd.log], [0], [dnl
+ISID_VLAN_ASGNS TLV too short
+])
+
+OVS_TRAFFIC_VSWITCHD_STOP(["/|WARN|ISID_VLAN_ASGNS TLV too short received on
ovs-p0/d"])
+AT_CLEANUP
--
2.38.1
_______________________________________________
dev mailing list
d...@openvswitch.org
https://mail.openvswitch.org/mailman/listinfo/ovs-dev
