From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 24 May 2022 20:58:38 GMT
Subject: Re: [PATCH 1/4] compat/win32/syslog: fix use-after-realloc
Message-ID: <xmqqy1yqfy0x.fsf@gitster.g>
In-Reply-To: <nycvar.QRO.7.76.6.2205241431400.352@tvgsbejvaqbjf.bet>

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

>>  		str = realloc(str, st_add(++str_len, 1));
>
> Since it has been raised elsewhere: Why is that `++str_len` not turned
> into an `st_add()`?
> ...
> Now you know,

I'd be more worried about a macro looking thing evalutating its
parameters more than once, though.  But unlike st_addN(), st_add()
is an inline function so we do not have to worry about that ;-)

>> @@ -50,6 +51,7 @@ void syslog(int priority, const char *fmt, ...)
>>  			warning_errno("realloc failed");
>>  			return;
>>  		}
>> +		pos = str + offset;

The adjustment using ofs is very much straight-forward.  Nicely
spotted and nicely corrected.

Thanks.