Re: [PATCH] avoid -Wuse-after-free [BZ #26779]

[Martin Sebor <msebor@gmail.com>]

On 1/18/22 02:48, Florian Weimer wrote:
> * Martin Sebor via Libc-alpha:
> 
>> GCC 12 features a couple of new warnings designed to detect uses
>> of pointers made invalid by the pointees lifetimes having ended.
>> Building Glibc with the enhanced GCC exposes a few such uses,
>> mostly after successful calls to realloc.  The attached patch
>> avoids the new warnings by converting the pointers to uintptr_t
>> first and using the converted integers instead.
>>
>> The patch suppresses all instances of the warning at the strictest
>> setting (-Wuse-after-free=3), which includes even uses in equality
>> expressions.  The default setting approved for GCC 12 is
>> -Wuse-after-free=2, which doesn't warn on such uses to accommodate
>> the pointer-adjustment-after-realloc idiom.  At the default setting,
>> the changes to ldconfig.c and setenv are not necessary.
> 
> Would you be able to split up this patch further?  It will help with
> eventually backporting parts of it.

Sure.  Let me fix the issues Paul pointed out and post a diff for
each file separately.

Martin

> 
> Thanks,
> Florian
>