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CVE-2017-13688/OLSR: Do bounds checks before we fetch data.

Browse Source 
While we're at it, clean up some other bounds checks, so we check that
we have a complete IPv4 message header if it's IPv4 and a complete IPv6
message header if it's IPv6.

This fixes a buffer over-read discovered by Bhargava Shastry,
SecT/TU Berlin.

Add tests using the capture files supplied by the reporter(s).
This commit is contained in:
Guy Harris 2017-08-23 19:26:37 -07:00 committed by Denis Ovsienko
parent 26b956739a
commit 0cb1b8a434
6 changed files with 36 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
print-olsr.c
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@ -359,10 +359,9 @@ olsr_print(netdissect_options *ndo,
} msgptr;
int msg_len_valid = 0;
ND_TCHECK2(*tptr, sizeof(struct olsr_msg4));
if (is_ipv6)
{
ND_TCHECK2(*tptr, sizeof(struct olsr_msg6));
msgptr.v6 = (const struct olsr_msg6 *) tptr;
msg_type = msgptr.v6->msg_type;
msg_len = EXTRACT_16BITS(msgptr.v6->msg_len);
@ -393,6 +392,7 @@ olsr_print(netdissect_options *ndo,
}
else /* (!is_ipv6) */
{
ND_TCHECK2(*tptr, sizeof(struct olsr_msg4));
msgptr.v4 = (const struct olsr_msg4 *) tptr;
msg_type = msgptr.v4->msg_type;
msg_len = EXTRACT_16BITS(msgptr.v4->msg_len);
@ -616,22 +616,25 @@ olsr_print(netdissect_options *ndo,
case OLSR_NAMESERVICE_MSG:
{
u_int name_entries = EXTRACT_16BITS(msg_data+2);
u_int addr_size = 4;
int name_entries_valid = 0;
u_int name_entries;
u_int addr_size;
int name_entries_valid;
u_int i;
if (is_ipv6)
addr_size = 16;
if ((name_entries > 0)
&& ((name_entries * (4 + addr_size)) <= msg_tlen))
name_entries_valid = 1;
if (msg_tlen < 4)
goto trunc;
ND_TCHECK2(*msg_data, 4);
name_entries = EXTRACT_16BITS(msg_data+2);
addr_size = 4;
if (is_ipv6)
addr_size = 16;
name_entries_valid = 0;
if ((name_entries > 0)
&& ((name_entries * (4 + addr_size)) <= msg_tlen))
name_entries_valid = 1;
ND_PRINT((ndo, "\n\t Version %u, Entries %u%s",
EXTRACT_16BITS(msg_data),
name_entries, (name_entries_valid == 0) ? " (invalid)" : ""));

2
tests/TESTLIST
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@ -575,6 +575,8 @@ lldp_8023_mtu-oobr lldp_8023_mtu-oobr.pcap lldp_8023_mtu-oobr.out -v -c1
bgp_vpn_rt-oobr bgp_vpn_rt-oobr.pcap bgp_vpn_rt-oobr.out -v -c1
cfm_sender_id-oobr cfm_sender_id-oobr.pcap cfm_sender_id-oobr.out -v -c1
isis-extd-isreach-oobr isis-extd-isreach-oobr.pcap isis-extd-isreach-oobr.out -v -c4
olsr-oobr-1 olsr-oobr-1.pcap olsr-oobr-1.out -v
olsr-oobr-2 olsr-oobr-2.pcap olsr-oobr-2.out -v
# bad packets from Katie Holly
mlppp-oobr mlppp-oobr.pcap mlppp-oobr.out

16
tests/olsr-oobr-1.out Normal file
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@ -0,0 +1,16 @@
IP truncated-ip - 2315 bytes missing! (tos 0x0, ttl 18, id 4111, offset 0, flags [+, DF, rsvd], proto UDP (17), length 5373, bad cksum 8e7f (->9764)!)
15.251.128.192.698 > 193.192.186.0.122: OLSRv4, seq 0x0800, length 2056
Nameservice Message (0x82), originator 126.198.193.192, ttl 26, hop 145
vtime 0.062s, msg-seq 0x0008, length 127[|olsr]
IP truncated-ip - 2315 bytes missing! (tos 0x0, ttl 18, id 4111, offset 0, flags [+, DF, rsvd], proto UDP (17), length 5373, bad cksum 8e7f (->975f)!)
16.0.128.192.698 > 193.192.186.0.122: OLSRv4, seq 0x0400, length 512
Powerinfo Message (0x80), originator 0.1.0.0, ttl 255, hop 255
vtime 0.500s, msg-seq 0x0000, length 9216 (invalid)
IP truncated-ip - 2315 bytes missing! (tos 0x0, ttl 18, id 4111, offset 0, flags [+, DF, rsvd], proto UDP (17), length 5373, bad cksum 8e7f (->9764)!)
15.251.128.192.698 > 193.192.186.0.122: OLSRv4, seq 0x0800, length 2056
Nameservice Message (0x82), originator 126.198.193.192, ttl 26, hop 145
vtime 0.062s, msg-seq 0x0008, length 100[|olsr]
IP truncated-ip - 2315 bytes missing! (tos 0x0, ttl 18, id 4111, offset 0, flags [+, DF, rsvd], proto UDP (17), length 5373, bad cksum 8e7f (->975f)!)
16.0.128.192.698 > 193.192.186.0.122: OLSRv4, seq 0x0800, length 2056
Nameservice Message (0x82), originator 126.198.193.192, ttl 26, hop 145
vtime 0.062s, msg-seq 0x5c50, length 185[|olsr]

BIN
tests/olsr-oobr-1.pcap Normal file
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3
tests/olsr-oobr-2.out Normal file
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@ -0,0 +1,3 @@
[|ether]
[|ether]
IP6 (flowlabel 0x06400, hlim 0, next-header UDP (17) payload length: 5401) 0:24::1e:a0a:141e.698 > 38fd:7f49:eaff:ffff:2025:7373:7562:2573.2: OLSRv6, seq 0x0201, length 5393[|olsr]

BIN
tests/olsr-oobr-2.pcap Normal file
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