From: Jorgen Loland
Date: December 16 2010 9:02am
Subject: Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3520)
 Bug#58207
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On 12/16/2010 09:21 AM, Martin Hansson wrote:
> Jorgen Loland skrev 2010-12-15 14.07:
>> Martin,
>>
>> The fix looks good, but the test case in the patch does not give
>> valgrind warning. Please provide a test case that is fixed by the
>> patch (e.g., the one reported in the bug). If you violently refuse to
>> replace this test, you can add one more instead.
> You did build with BUILD/compile-pentium-valgrind-max, right? If you
> still don't see it you might try to revert to the same revision as I
> committed into.
>
> Does the test case in the bug report give valgrind warnings but mine
> doesn't? If they do then that's serious enough, BUT... things actually
> changed *while* I was working on the bug. First time around, the first
> test caused a core dump. Then when I pulled the latest changes it
> didn't, and then two days later it caused a crash again. The bug is that
> we get a totally runaway pointer, so it's sensitive to just about anything.

I compiled with compile-amd64-valgrind-max.

Without your code changes, the test case in the bug report gives valgrind 
warnings like this:

==7710== Invalid read of size 1
==7710==    at 0x4C28E61: memcpy (mc_replace_strmem.c:497)
==7710==    by 0x76A3C3: create_tmp_table(THD*, TMP_TABLE_PARAM*, List<Item>&, 
st_order*, bool, bool, unsigned long long, unsigned long long, char*) 
(sql_select.cc:10412)

These warnings go away when I apply your fix. The test case you added does not 
give valgrind warning before applying your code changes.

-- 
Jørgen Løland | Senior Software Engineer | +47 73842138
Oracle MySQL
Trondheim, Norway