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NULL pointer dereference in domain_dname() #30

fcambus opened this issue Jul 31, 2019 · 1 comment

NULL pointer dereference in domain_dname() #30

fcambus opened this issue Jul 31, 2019 · 1 comment


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@fcambus fcambus commented Jul 31, 2019


While fuzzing nsd-checkzone with Honggfuzz, I found a NULL pointer dereference in the domain_dname() function.

I believe it was introduced by commit b4528a3.

Attaching a reproducer (gzipped so GitHub accepts it): zone04.gz

Issue can be reproduced by running:

nsd-checkzone all.rr zone04

In namedb.h L270 returning domain->dname results in a NULL pointer dereference because domain ends up being NULL:

#0  0x0000041f7a8f3e2b in domain_dname (domain=0x0) at namedb.h:270
270             return (dname_type *) domain->dname;
@wcawijngaards wcawijngaards self-assigned this Jul 31, 2019

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@wcawijngaards wcawijngaards commented Jul 31, 2019

Hi again! Thanks for the fuzzing action, this reveals nice corner cases. The domain name is missing and it tries to print it in the error message, but the earlier parse error makes the domain name NULL causing it to error in the error printout. I added a check for the domain name working.

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