Re: Avoid possible deference NULL pointer (src/backend/optimizer/path/allpaths.c)

From: Daniel Gustafsson <daniel(at)yesql(dot)se>
To: Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Avoid possible deference NULL pointer (src/backend/optimizer/path/allpaths.c)
Date: 2025-02-05 17:07:50
Message-ID: E2392586-80AF-4FEE-8811-940F1F0DD194@yesql.se
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> On 5 Jan 2025, at 00:29, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> wrote:
>
> Hi.
>
> Per Coverity.
>
> All call sites of function *get_cheapest_path_for_pathkeys* checks
> for NULL returns.
>
> So, it is highly likely that the function will return NULL.
>
> IMO, the Assert in this particular call, is not fully effective.
>
> Fix removing the Assert and always check if the return is NULL.

Yet the author wrote an Assert here (over a decade ago), so rather than blindly
changing that it seems reasonable to motivate a patch like this with an
investigation on what the Assert means here. The fact that Coverity complains
is far from conclusive evidence that something is wrong.

--
Daniel Gustafsson

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