Re: [edk2-devel] [edk2-libc Patch 1/1] edk2-libc/StdLib: Fix uninitialized global variable

["Michael Brown" <mcb30@ipxe.org>]

On 25/07/2023 17:07, Jayaprakash, N wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4506
> 
> res_init() is called from different places in sockets library. It depends
> on global _res variable containing a state.
> 
> The problem is that if __BIND_RES_TEXT macro is not defined, _res is not
> initialized. Depending on compiler and build optimization this can fill the
> variable with garbage that is later used by res_init().
> 
> Fix is trivial - explicitly initialize _res.
>   
>   struct __res_state _res
> -# if defined(__BIND_RES_TEXT)
> +#if defined(__BIND_RES_TEXT)
>       = { RES_TIMEOUT, }  /* Motorola, et al. */
> -# endif
> +#endif
> +    = {0}
> +#endif
>       ;

NAK.  This is very wrong.

Firstly, your patch introduces unnecessary whitespace changes and so is 
unnecessarily cumbersome to review.

Secondly, the patch creates an invalid "#if ... #endif ... #endif" 
combination.  I suspect that you meant to use "#else" in the middle.

Thirdly, and most importantly, the whole patch is entirely unnecessary. 
As a variable with static storage duration, if no explicit initializer 
is provided then the C language guarantees that the value will be 
initialized to zero anyway.

Thanks,

Michael



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