Remote crash in MaraDNS 2.0.13 and git master

[Ondřej Surý <ondrej () sury org>]

Hi,

while playing with fuzzing the DNS servers with AFL (2.35b) I found a
remote crash bug in MaraDNS 2.0.13 js_readuint16. It can be also
reproduced using https://github.com/samboy/MaraDNS/ master branch.

Attached is patch to allow the fuzzing (it overrides getudp() with
read(0, ..)), the input data that crashes MaraDNS, and the bt full
output.

Please assign CVE, I would provide a patch, but MaraDNS code is
extremely hard to navigate for me, so I'll leave the fix for the code
author.

AFL has finished only 1 cycle (and found the 1 unique crash), so I'll
keep it running for a while.

Cheers,
-- 
Ondřej Surý <ondrej () sury org>
Knot DNS (https://www.knot-dns.cz/) – a high-performance DNS server
Knot Resolver (https://www.knot-resolver.cz/) – secure, privacy-aware,
fast DNS(SEC) resolver
Vše pro chleba (https://vseprochleba.cz) – Mouky ze mlýna a potřeby pro
pečení chleba všeho druhu

Attachment: maradns.btfull
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Attachment: allow-fuzzing.patch
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Attachment: id:000000,sig:11,src:007564,op:havoc,rep:32
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