[Dnsmasq-discuss] DNSSEC Retry causes SEGFAULT

Dominik dl6er at dl6er.de
Sat Oct 5 11:22:16 BST 2019

Hey all,

I'm reporting a bug on behold of another user that does not want to
contact this mailing list himself.

Short summary: With DNSSEC enabled, the user sees a crash when dnsmasq
wants to retry a query after the upstream DNS server responded before
with "REFUSED DNSKEY". At least this is my theory so far.

This crash happens with dnsmasq v2.80.

The backtrace shows that the error is encountered at
>> if (forward->sentto->addr.sa.sa_family == AF_INET)

With gdb, we saw that the crash happens when dnsmasq tries to access
(gdb) p forward
$1 = (struct frec *) 0x5569e433b0e0
(gdb) p forward->sentto
$2 = (struct server *) 0x0
(gdb) p forward->sentto->addr
Cannot access memory at address 0x0
(gdb) p forward->sentto->addr.sa
Cannot access memory at address 0x0
(gdb) p forward->sentto->addr.sa.sa_family
Cannot access memory at address 0x0

Further details can be found in the issue ticket below.
I'll man-in-the-middle things back and forth if necessary.

Best regards,

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