Message-ID: <604e8e01-90cb-438e-abbb-911c58399877@gmail.com>
Date: Sun, 19 Oct 2025 20:34:02 -0500
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Subject: Re: [PATCH] Fix POSIX compliance in pgwin32_unsetenv()
To: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-hackers@postgresql.org
References: <b6a1e52b-d808-4df7-87f7-2ff48d15003e@gmail.com>
 <aPWKJwVjX53MJtfQ@paquier.xyz>
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From: Bryan Green <dbryan.green@gmail.com>
In-Reply-To: <aPWKJwVjX53MJtfQ@paquier.xyz>
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On 10/19/25 20:02, Michael Paquier wrote:
> On Sat, Oct 18, 2025 at 01:26:40PM -0500, Bryan Green wrote:
>> I noticed that pgwin32_unsetenv() in src/port/win32env.c lacks the input
>> validation that its sibling function pgwin32_setenv() has (lines 126-132).
>>
>> Without these checks, the function will crash on NULL input via
>> strlen(NULL), and will accept empty strings or strings containing '=' in
>> violation of POSIX.1-2008.
>>
>> The attached patch adds the same validation that pgwin32_setenv already
>> does, making the two functions consistent.  This is purely defensive - it
>> only affects callers passing invalid arguments.
> 
> I presume that you have tried to use this routine on some external
> code on WIN32 to note that it was just crashing.
> 
> The current state of pgwin32_unsetenv() dates back to 0154345078fb.
> The POSIX checks of setenv() are more recent than that, as in
> 7ca37fb0406b down to v14.  I agree that the inconsistency in handling
> the input arguments is annoying, so if there are no objections let's
> apply the same checks down to v14 like the setenv() piece.  It's
> better than a hard crash.
> --
> Michael

I have been going through all of the windows code line by line.  That is 
how I initially noticed this.  I then wrote a program to exercise the 
code and confirm the crash. I agree it should be backported.

BG