[dev] frr 8.4.x and 8.5 trigger assertion in bgpd/bgp_lcommunity.c:236

[Kurt Jaeger]

Hi!

> This caused bgpd to terminate on several boxes this morning:
> 
> 2023/04/18 08:43:47 BGP: bgpd/bgp_lcommunity.c:236: set_lcommunity_string(): assertion ((unsigned int)len < str_buf_sz) failed
> BGP: Received signal 6 at 1681800227 (si_addr 0x0); aborting...
> 
> OS: FreeBSD 13.1p3. frr was 8.4.x and 8.5. So someone is sending
> strange things... ?
> 
> 7.5.1 is not affected...
> 
> Any ideas on how to avoid the assert ?

There's the lookup for community aliases added in that function:

                const char *com2alias =
                        translate_alias ? bgp_community2alias(lcsb) : lcsb;
 
                len = strlcat(str_buf, com2alias, str_buf_sz);

and it seems to trigger the issue.

-- 
pi at opsec.eu            +49 171 3101372                    Now what ?