| From 9efd9a47db4f13ebf88c2ffe14301d7441bcb40d Mon Sep 17 00:00:00 2001 |
| From: Donatas Abraitis <donatas@opensourcerouting.org> |
| Date: Tue, 22 Aug 2023 22:52:04 +0300 |
| Subject: [PATCH 1/2] bgpd: Do not process NLRIs if the attribute length is |
| zero |
| |
| ``` |
| 3 0x00007f423aa42476 in __GI_raise (sig=sig@entry=11) at ../sysdeps/posix/raise.c:26 |
| 4 0x00007f423aef9740 in core_handler (signo=11, siginfo=0x7fffc414deb0, context=<optimized out>) at lib/sigevent.c:246 |
| 5 <signal handler called> |
| 6 0x0000564dea2fc71e in route_set_aspath_prepend (rule=0x564debd66d50, prefix=0x7fffc414ea30, object=0x7fffc414e400) |
| at bgpd/bgp_routemap.c:2258 |
| 7 0x00007f423aeec7e0 in route_map_apply_ext (map=<optimized out>, prefix=prefix@entry=0x7fffc414ea30, |
| match_object=match_object@entry=0x7fffc414e400, set_object=set_object@entry=0x7fffc414e400, pref=pref@entry=0x0) at lib/routemap.c:2690 |
| 8 0x0000564dea2d277e in bgp_input_modifier (peer=peer@entry=0x7f4238f59010, p=p@entry=0x7fffc414ea30, attr=attr@entry=0x7fffc414e770, |
| afi=afi@entry=AFI_IP, safi=safi@entry=SAFI_UNICAST, rmap_name=rmap_name@entry=0x0, label=0x0, num_labels=0, dest=0x564debdd5130) |
| at bgpd/bgp_route.c:1772 |
| 9 0x0000564dea2df762 in bgp_update (peer=peer@entry=0x7f4238f59010, p=p@entry=0x7fffc414ea30, addpath_id=addpath_id@entry=0, |
| attr=0x7fffc414eb50, afi=afi@entry=AFI_IP, safi=<optimized out>, safi@entry=SAFI_UNICAST, type=9, sub_type=0, prd=0x0, label=0x0, |
| num_labels=0, soft_reconfig=0, evpn=0x0) at bgpd/bgp_route.c:4374 |
| 10 0x0000564dea2e2047 in bgp_nlri_parse_ip (peer=0x7f4238f59010, attr=attr@entry=0x7fffc414eb50, packet=0x7fffc414eaf0) |
| at bgpd/bgp_route.c:6249 |
| 11 0x0000564dea2c5a58 in bgp_nlri_parse (peer=peer@entry=0x7f4238f59010, attr=attr@entry=0x7fffc414eb50, |
| packet=packet@entry=0x7fffc414eaf0, mp_withdraw=mp_withdraw@entry=false) at bgpd/bgp_packet.c:339 |
| 12 0x0000564dea2c5d66 in bgp_update_receive (peer=peer@entry=0x7f4238f59010, size=size@entry=109) at bgpd/bgp_packet.c:2024 |
| 13 0x0000564dea2c901d in bgp_process_packet (thread=<optimized out>) at bgpd/bgp_packet.c:2933 |
| 14 0x00007f423af0bf71 in event_call (thread=thread@entry=0x7fffc414ee40) at lib/event.c:1995 |
| 15 0x00007f423aebb198 in frr_run (master=0x564deb73c670) at lib/libfrr.c:1213 |
| 16 0x0000564dea261b83 in main (argc=<optimized out>, argv=<optimized out>) at bgpd/bgp_main.c:505 |
| ``` |
| |
| With the configuration: |
| |
| ``` |
| frr version 9.1-dev-MyOwnFRRVersion |
| frr defaults traditional |
| hostname ip-172-31-13-140 |
| log file /tmp/debug.log |
| log syslog |
| service integrated-vtysh-config |
| ! |
| debug bgp keepalives |
| debug bgp neighbor-events |
| debug bgp updates in |
| debug bgp updates out |
| ! |
| router bgp 100 |
| bgp router-id 9.9.9.9 |
| no bgp ebgp-requires-policy |
| bgp bestpath aigp |
| neighbor 172.31.2.47 remote-as 200 |
| ! |
| address-family ipv4 unicast |
| neighbor 172.31.2.47 default-originate |
| neighbor 172.31.2.47 route-map RM_IN in |
| exit-address-family |
| exit |
| ! |
| route-map RM_IN permit 10 |
| set as-path prepend 200 |
| exit |
| ! |
| ``` |
| |
| The issue is that we try to process NLRIs even if the attribute length is 0. |
| |
| Later bgp_update() will handle route-maps and a crash occurs because all the |
| attributes are NULL, including aspath, where we dereference. |
| |
| According to the RFC 4271: |
| |
| A value of 0 indicates that neither the Network Layer |
| Reachability Information field nor the Path Attribute field is |
| present in this UPDATE message. |
| |
| But with a fuzzed UPDATE message this can be faked. I think it's reasonable |
| to skip processing NLRIs if both update_len and attribute_len are 0. |
| |
| Reported-by: Iggy Frankovic <iggyfran@amazon.com> |
| Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org> |
| |
| Upstream-Status: Backport [https://github.com/FRRouting/frr/commit/28ccc24d38df1d51ed8a563507e5d6f6171fdd38] |
| |
| CVE: CVE-2023-41358 |
| |
| Signed-off-by: Robert Yang <liezhi.yang@windriver.com> |
| --- |
| bgpd/bgp_packet.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c |
| index ec54943f3..3c2e73c59 100644 |
| --- a/bgpd/bgp_packet.c |
| +++ b/bgpd/bgp_packet.c |
| @@ -1951,7 +1951,7 @@ static int bgp_update_receive(struct peer *peer, bgp_size_t size) |
| /* Network Layer Reachability Information. */ |
| update_len = end - stream_pnt(s); |
| |
| - if (update_len) { |
| + if (update_len && attribute_len) { |
| /* Set NLRI portion to structure. */ |
| nlris[NLRI_UPDATE].afi = AFI_IP; |
| nlris[NLRI_UPDATE].safi = SAFI_UNICAST; |
| -- |
| 2.35.5 |
| |