Re: [patch][gcc12-changes] Add a new item about the support for automatic static variable initialization

[Qing Zhao <qing.zhao@oracle.com>]

> On Sep 29, 2021, at 5:39 AM, Richard Biener <rguenther@suse.de> wrote:
> 
> On Tue, 28 Sep 2021, Kees Cook wrote:
> 
>> On Tue, Sep 28, 2021 at 08:31:13PM +0000, Qing Zhao wrote:
>>> Hi,
>>> 
>>> This is the patch for the gcc12 changes  per your request. 
>>> 
>>> Kees provided most of the wording. 
>>> 
>>> Please take a look and let’s know whether it’s good for commit?
>>> 
>>> thanks.
>>> 
>>> Qing
>>> 
>>> ================================================
>>> 
>>> 
>>> From: qing zhao <qing.zhao@oracle.com>
>>> Date: Tue, 28 Sep 2021 12:01:42 -0700
>>> Subject: [PATCH] gcc-12/changes.html: Uninitialized stack variables
>>> initialization update
>>> 
>>> 	* htdocs/gcc-12/changes.html (Eliminating uninitialized variables):
>>> 	Item about the support for automatic static variable initialization.
>>> ---
>>> htdocs/gcc-12/changes.html | 19 +++++++++++++++++++
>>> 1 file changed, 19 insertions(+)
>>> 
>>> diff --git a/htdocs/gcc-12/changes.html b/htdocs/gcc-12/changes.html
>>> index 1f156a9..8e2979c 100644
>>> --- a/htdocs/gcc-12/changes.html
>>> +++ b/htdocs/gcc-12/changes.html
>>> @@ -245,6 +245,25 @@ a work-in-progress.</p>
>>> <!-- .................................................................. -->
>>> <h2>Other significant improvements</h2>
>>> 
>>> +<h3 id="uninitialized">Eliminating uninitialized variables</h3>
>>> +
>>> +<ul>
>>> +  <li>GCC can now initialize all stack variables implicitly, including
>>> +      padding. This is intended to eliminate all classes of uninitialized
>>> +      stack variable flaws. Lack of explicit initialization will still
>>> +      warn when <code>-Wuninitialized</code> is active. For best
>>> +      debugging, use of the new command-line option
>>> +      <code>-ftrivial-auto-var-init=pattern</code> can be used to fill
>>> +      variables with a repeated 0xFE pattern, which tends to illuminate
>>> +      many bugs (e.g. pointers receive invalid addresses, sizes and indices
>>> +      are very large). For best production results, the new command-line
>>> +      option <code>-ftrivial-auto-var-init=zero</code> can be used to
>>> +      fill variables with 0x00, which tends to provide a safer state for
>>> +      bugs (e.g. pointers are NULL, strings are NULL filled, and sizes
>> 
>> Minor nit: I've always been corrected that "NULL" refers to a pointer, and
>> "NUL" refers to the "null character", so the latter use of NULL should be
>> "NUL": ... pointers are NULL, strings are NUL filled, and size ...
>> 
>> I mix this up all the time, so apologies if that got introduced by me!
>> :)
> 
> Also things like 0xFE and NULL should be wrapped in <code></code>, 
> otherwise it looks good to me.

Okay, will update them before committing.

Thanks.

Qing
> 
> Thanks,
> Richard.
> 
>> -Kees
>> 
>>> +      and indices are 0).
>>> +  </li>
>>> +</ul>
>>> +
>>> <h3 id="debug">Debugging formats</h3>
>>> 
>>> <ul>
>>> -- 
>>> 1.9.1
>>> 
>>> 
>> 
>> 
> 
> -- 
> Richard Biener <rguenther@suse.de>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)