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bgpd: Check the actual remaining stream length before taking TLV value
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```
    0 0xb50b9f898028 in __sanitizer_print_stack_trace (/home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/.libs/bgpd+0x368028) (BuildId: 3292703ed7958b20076550c967f879db8dc27ca7)
    1 0xb50b9f7ed8e4 in fuzzer::PrintStackTrace() (/home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/.libs/bgpd+0x2bd8e4) (BuildId: 3292703ed7958b20076550c967f879db8dc27ca7)
    2 0xb50b9f7d4d9c in fuzzer::Fuzzer::CrashCallback() (/home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/.libs/bgpd+0x2a4d9c) (BuildId: 3292703ed7958b20076550c967f879db8dc27ca7)
    3 0xe0d12d7469cc  (linux-vdso.so.1+0x9cc) (BuildId: 1a77697e9d723fe22246cfd7641b140c427b7e11)
    4 0xe0d12c88f1fc in __pthread_kill_implementation nptl/pthread_kill.c:43:17
    5 0xe0d12c84a678 in gsignal signal/../sysdeps/posix/raise.c:26:13
    6 0xe0d12c83712c in abort stdlib/abort.c:79:7
    7 0xe0d12d214724 in _zlog_assert_failed /home/ubuntu/frr-public/frr_public_private-libfuzzer/lib/zlog.c:789:2
    8 0xe0d12d1285e4 in stream_get /home/ubuntu/frr-public/frr_public_private-libfuzzer/lib/stream.c:324:3
    9 0xb50b9f8e47c4 in bgp_attr_encap /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_attr.c:2758:3
    10 0xb50b9f8dcd38 in bgp_attr_parse /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_attr.c:3783:10
    11 0xb50b9faf74b4 in bgp_update_receive /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:2383:20
    12 0xb50b9faf1dcc in bgp_process_packet /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_packet.c:4075:11
    13 0xb50b9f8c90d0 in LLVMFuzzerTestOneInput /home/ubuntu/frr-public/frr_public_private-libfuzzer/bgpd/bgp_main.c:582:3
```

Reported-by: Iggy Frankovic <[email protected]>
Signed-off-by: Donatas Abraitis <[email protected]>
(cherry picked from commit 0998b38)
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@ton31337 @mergify
ton31337 authored and mergify[bot] committed Jul 31, 2024
1 parent 5519607 commit ab70eee
Showing 1 changed file with 8 additions and 0 deletions.
8 changes: 8 additions & 0 deletions bgpd/bgp_attr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2687,6 +2687,14 @@ static int bgp_attr_encap(struct bgp_attr_parser_args *args)
args->total);
}

if (STREAM_READABLE(BGP_INPUT(peer)) < sublength) {
zlog_err("Tunnel Encap attribute sub-tlv length %d exceeds remaining stream length %zu",
sublength, STREAM_READABLE(BGP_INPUT(peer)));
return bgp_attr_malformed(args,
BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
args->total);
}

/* alloc and copy sub-tlv */
/* TBD make sure these are freed when attributes are released */
tlv = XCALLOC(MTYPE_ENCAP_TLV,
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