From b685ab5e1bdec0848502c20e9596b9716b236639 Mon Sep 17 00:00:00 2001 From: Donatas Abraitis Date: Thu, 13 Jun 2024 08:12:10 +0300 Subject: [PATCH] bgpd: Check if we have really enough data before doing memcpy for FQDN capability We advance data pointer (data++), but we do memcpy() with the length that is 1-byte over, which is technically heap overflow. ``` ==411461==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x50600011da1a at pc 0xc4f45a9786f0 bp 0xffffed1e2740 sp 0xffffed1e1f30 READ of size 4 at 0x50600011da1a thread T0 0 0xc4f45a9786ec in __asan_memcpy (/home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/.libs/bgpd+0x3586ec) (BuildId: e794c5f796eee20c8973d7efb9bf5735e54d44cd) 1 0xc4f45abf15f8 in bgp_dynamic_capability_fqdn /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:3457:4 2 0xc4f45abdd408 in bgp_capability_msg_parse /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:3911:4 3 0xc4f45abdbeb4 in bgp_capability_receive /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:3980:9 4 0xc4f45abde2cc in bgp_process_packet /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:4109:11 5 0xc4f45a9b6110 in LLVMFuzzerTestOneInput /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_main.c:582:3 ``` Found by fuzzing. Reported-by: Iggy Frankovic Signed-off-by: Donatas Abraitis --- bgpd/bgp_packet.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c index 3f38790cbd..e54766aa39 100644 --- a/bgpd/bgp_packet.c +++ b/bgpd/bgp_packet.c @@ -3437,7 +3437,7 @@ static void bgp_dynamic_capability_fqdn(uint8_t *pnt, int action, } len = *data; - if (data + len > end) { + if (data + len + 1 > end) { zlog_err("%pBP: Received invalid FQDN capability length (host name) %d", peer, hdr->length); return; @@ -3468,7 +3468,7 @@ static void bgp_dynamic_capability_fqdn(uint8_t *pnt, int action, /* domainname */ len = *data; - if (data + len > end) { + if (data + len + 1 > end) { zlog_err("%pBP: Received invalid FQDN capability length (domain name) %d", peer, len); return; -- 2.39.5