[Freeipa-devel] [PATCH 0234] Prevent NULL dereference before sync_concurr_limit_signal() calls

Petr Spacek pspacek at redhat.com
Wed Apr 9 14:38:24 UTC 2014

On 9.4.2014 15:20, Tomas Hozza wrote:
> On 04/09/2014 02:07 PM, Petr Spacek wrote:
>> Hello,
>> Prevent NULL dereference before sync_concurr_limit_signal() calls.
>> Missing check was causing NULL dereference in case where
>> manager_get_ldap_instance() failed. This typically happens when BIND
>> is processing LDAP updates during shutdown.
>> I noticed this crash during sanity testing 4.2 release...
>> Please review it ASAP so I can release 4.3.
>> How to reproduce the problem:
>> Run BIND manually from console:
>> $ named -4 -g -u named -m record -n 10
>> and press Ctrl+C "almost immediately".
>> Sometimes it shutdowns cleanly and sometimes you can see a crash:
>> Thank you for your time!
> ACK.
> I'm not able to reproduce the issue, but the patch looks reasonable and
> should not break anything.

Thanks. I have modified the patch once again before push to silence Clang 
warnings about potential NULL-inst deference on following lines:

if (dns_name_dynamic(&name))
     dns_name_free(&name, inst->mctx);

In reality the NULL dereference cannot happen because it is guarded by 
condition in dns_name_dynamic().

This is not a problem now but the behavior depends on internal implementation 
in BIND. It is definitely better to add explicit check to stay safe ...

Petr^2 Spacek
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