Re: Please, fix!!! The backend can crash on your system!

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Alexis Wilke <alexis_wilke(at)yahoo(dot)com>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Please, fix!!! The backend can crash on your system!
Date: 2001-03-29 13:39:04
Message-ID: 200103291339.IAA23907@candle.pha.pa.us
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In the current sources, I see:

for (lineoff = FirstOffsetNumber; lineoff <= max; lineoff++)

so it looks like we have this fixed. You can check the 7.1RC1.

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> ============================================================================
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>
> Your name : Alexis Wilke
> Your email address : alexis(at)m2osw(dot)com
>
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> System Configuration
> ---------------------
> Architecture (example: Intel Pentium) : trust me, doesn't matter
>
> Operating System (example: Linux 2.0.26 ELF) : trust me, doesn't matter
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> PostgreSQL version (example: PostgreSQL-7.0): since PostgreSQL-6.5.x
> and still in the code
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> Please enter a FULL description of your problem:
> ------------------------------------------------
>
> It crashes when pg_database is too large. This is because
> the index is compare to max with <= instead of <. I already
> fixed the bug on my system. That's at line
>
>
>
> Please describe a way to repeat the problem. Please try to provide a
> concise reproducible example, if at all possible:
> ----------------------------------------------------------------------
>
> Create many database (or create/destroy the same many times).
>
> Once the pg_database is more than one page (is 16Kb or more) then it
> starts
> crashing. (may not crash on all systems, but trust me, my fix
> will work GREAT).
>
>
>
> If you know how this problem might be fixed, list the solution below:
> ---------------------------------------------------------------------
>
> Okay, so go in the following file:
>
> ./src/backend/utils/misc/database.c
>
> and move to the line #183 (V7.0.1)
>
> There, fix the for() as is:
>
> for(i = 0; i < max; i++)
>
> Why? Well, because 'i' starts at 0, therefore, you
> can't access the tuple number 'max'. If you look in
> other source files, you will quickly see that all
> these for() loops are starting with an index of
> 1 and use some special functions/macros to access
> the tuple data.
>
>
>
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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