Message-ID: <b316ad5b-6c94-4f23-8d24-57ec4a430c10@iki.fi>
Date: Mon, 28 Oct 2024 14:13:25 +0200
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Subject: Re: Avoid possible overflow (src/port/bsearch_arg.c)
To: Ranier Vilela <ranier.vf@gmail.com>,
 Nathan Bossart <nathandbossart@gmail.com>, Tomas Vondra <tv@fuzzy.cz>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
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 <ZwWkBb2gxs5fGttK@nathan>
 <CAEudQAr8KZET1ogPnT7esb7YdYbmJyFZWo-OnP+FgoKeL+N31A@mail.gmail.com>
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From: Heikki Linnakangas <hlinnaka@iki.fi>
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On 09/10/2024 19:16, Ranier Vilela wrote:
> Em ter., 8 de out. de 2024 às 18:28, Nathan Bossart 
> <nathandbossart@gmail.com <mailto:nathandbossart@gmail.com>> escreveu:
> 
>     On Tue, Oct 08, 2024 at 04:09:00PM -0300, Ranier Vilela wrote:
>      > The port function *bsearch_arg* mimics the C function
>      > *bsearch*.
>      >
>      > The API signature is:
>      > void *
>      > bsearch_arg(const void *key, const void *base0,
>      > size_t nmemb, size_t size,
>      > int (*compar) (const void *, const void *, void *),
>      > void *arg)
>      >
>      > So, the parameter *nmemb* is size_t.
>      > Therefore, a call with nmemb greater than INT_MAX is possible.
>      >
>      > Internally the code uses the *int* type to iterate through the
>     number of
>      > members, which makes overflow possible.
> 
>     I traced this back to commit bfa2cee (v14), which both moved
>     bsearch_arg()
>     to its current location and adjusted the style a bit.  Your patch looks
>     reasonable to me.
> 
> Thanks for looking.

Committed, thanks.

Based on the original discussion on bfa2cee, I couldn't figure out where 
exactly this new bsearch implementation originated from, but googling 
around, probably *BSD or libiberty. Tomas, do you remember? Not that it 
matters, but I'm curious.

Some of those other implementations have fixed this, others have not. 
And they all seem to also have the "involes" typo in the comment that we 
fixed in commit 7ef8b52cf07 :-). Ranier, you might want to submit this 
fix to those other projects too.

-- 
Heikki Linnakangas
Neon (https://neon.tech)