[Dnsmasq-discuss] Segfault problem with --conntrack option

Giacomo Tazzari giacomo.tazzari at gmail.com
Sun Apr 21 17:34:47 BST 2013


I encountered a bug that makes dnsmasq segfaults when the --conntrack
option is enabled.
I am not entirely sure how to reproduce it: on my router (an Ubuntu server)
it seems to occur sometimes when a remote DNS responds with ServFail to an
A query.

Anyway, after compiling with debugging symbols, I figured out how to fix it:

$ diff dnsmasq-2.66/src/forward.c dnsmasq-2.66-fixed/src/forward.c
<                 if (option_bool(OPT_CONNTRACK))
>                 if (udpaddr && option_bool(OPT_CONNTRACK))

Otherwise get_incoming_mark() will crash when it tries to dereference
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