From f2bc4e6847b222ed8fbd460fbba9aa69d1bf8d0e Mon Sep 17 00:00:00 2001 From: Donatas Abraitis Date: Fri, 20 Oct 2023 17:49:18 +0300 Subject: [PATCH] bgpd: Handle MP_REACH_NLRI malformed packets with session reset Upstream: yes References: CVE-2023-46752,bsc#1216627,https://github.com/FRRouting/frr/pull/14645/commits/b08afc81c60607a4f736f418f2e3eb06087f1a35 Avoid crashing bgpd. ``` (gdb) bgp_mp_reach_parse (args=, mp_update=0x7fffffffe140) at bgpd/bgp_attr.c:2341 2341 stream_get(&attr->mp_nexthop_global, s, IPV6_MAX_BYTELEN); (gdb) stream_get (dst=0x7fffffffe1ac, s=0x7ffff0006e80, size=16) at lib/stream.c:320 320 { (gdb) 321 STREAM_VERIFY_SANE(s); (gdb) 323 if (STREAM_READABLE(s) < size) { (gdb) 34 return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest)); (gdb) Thread 1 "bgpd" received signal SIGSEGV, Segmentation fault. 0x00005555556e37be in route_set_aspath_prepend (rule=0x555555aac0d0, prefix=0x7fffffffe050, object=0x7fffffffdb00) at bgpd/bgp_routemap.c:2282 2282 if (path->attr->aspath->refcnt) (gdb) ``` With the configuration: ``` neighbor 127.0.0.1 remote-as external neighbor 127.0.0.1 passive neighbor 127.0.0.1 ebgp-multihop neighbor 127.0.0.1 disable-connected-check neighbor 127.0.0.1 update-source 127.0.0.2 neighbor 127.0.0.1 timers 3 90 neighbor 127.0.0.1 timers connect 1 address-family ipv4 unicast redistribute connected neighbor 127.0.0.1 default-originate neighbor 127.0.0.1 route-map RM_IN in exit-address-family ! route-map RM_IN permit 10 set as-path prepend 200 exit ``` Reported-by: Iggy Frankovic Signed-off-by: Donatas Abraitis (cherry picked from commit b08afc81c60607a4f736f418f2e3eb06087f1a35) Signed-off-by: Marius Tomaschewski diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c index 5c028c854c..42a2342f6f 100644 --- a/bgpd/bgp_attr.c +++ b/bgpd/bgp_attr.c @@ -2224,7 +2224,7 @@ int bgp_mp_reach_parse(struct bgp_attr_parser_args *args, mp_update->afi = afi; mp_update->safi = safi; - return BGP_ATTR_PARSE_EOR; + return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_MAL_ATTR, 0); } mp_update->afi = afi; @@ -3405,10 +3405,6 @@ enum bgp_attr_parse_ret bgp_attr_parse(struct peer *peer, struct attr *attr, goto done; } - if (ret == BGP_ATTR_PARSE_EOR) { - goto done; - } - if (ret == BGP_ATTR_PARSE_ERROR) { flog_warn(EC_BGP_ATTRIBUTE_PARSE_ERROR, "%s: Attribute %s, parse error", peer->host, diff --git a/bgpd/bgp_attr.h b/bgpd/bgp_attr.h index 4963ea64d0..23767153b2 100644 --- a/bgpd/bgp_attr.h +++ b/bgpd/bgp_attr.h @@ -382,7 +382,6 @@ enum bgp_attr_parse_ret { /* only used internally, send notify + convert to BGP_ATTR_PARSE_ERROR */ BGP_ATTR_PARSE_ERROR_NOTIFYPLS = -3, - BGP_ATTR_PARSE_EOR = -4, }; struct bpacket_attr_vec_arr; diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c index 1ef421028f..20c642190b 100644 --- a/bgpd/bgp_packet.c +++ b/bgpd/bgp_packet.c @@ -2027,8 +2027,7 @@ static int bgp_update_receive(struct peer *peer, bgp_size_t size) * Non-MP IPv4/Unicast EoR is a completely empty UPDATE * and MP EoR should have only an empty MP_UNREACH */ - if ((!update_len && !withdraw_len && nlris[NLRI_MP_UPDATE].length == 0) - || (attr_parse_ret == BGP_ATTR_PARSE_EOR)) { + if (!update_len && !withdraw_len && nlris[NLRI_MP_UPDATE].length == 0) { afi_t afi = 0; safi_t safi; struct graceful_restart_info *gr_info; @@ -2049,9 +2048,6 @@ static int bgp_update_receive(struct peer *peer, bgp_size_t size) && nlris[NLRI_MP_WITHDRAW].length == 0) { afi = nlris[NLRI_MP_WITHDRAW].afi; safi = nlris[NLRI_MP_WITHDRAW].safi; - } else if (attr_parse_ret == BGP_ATTR_PARSE_EOR) { - afi = nlris[NLRI_MP_UPDATE].afi; - safi = nlris[NLRI_MP_UPDATE].safi; } if (afi && peer->afc[afi][safi]) { -- 2.35.3