Re: [PING 2] [PATCH] enhance buffer overflow warnings (and c/53562)

[Martin Sebor <msebor@gmail.com>]

I'm still looking for a review of the patch below, first posted
on 10/28 and last updated/pinged last Wednesday:

   https://gcc.gnu.org/ml/gcc-patches/2016-11/msg00896.html

Thanks

On 11/09/2016 03:49 PM, Martin Sebor wrote:
> The attached minor update to the patch also resolves bug 77784 that
> points out that -Wformat-length issues a warning also issued during
> the expansion of some of the __builtin___sprintf_chk intrinsics.
>
> Martin
>
> On 11/04/2016 02:16 PM, Martin Sebor wrote:
>> Attached is an update to the patch that takes into consideration
>> the feedback I got.  It goes back to adding just one option,
>> -Wstringop-overflow, as in the original, while keeping the Object
>> Size type as an argument.  It uses type-1 as the default setting
>> for string functions (strcpy et al.) and, unconditionally, type-0
>> for raw memory functions (memcpy, etc.)
>>
>> I retested Binutils 2.27 and the Linux kernel again with this patch
>> and also added Glibc, and it doesn't complain about anything (both
>> Binutils and the kernel also build cleanly with an unpatched GCC
>> with_FORTIFY_SOURCE=2 or its rough equivalent for the kernel).
>> The emit-rtl.c warning (bug 78174) has also been suppressed by
>> the change to bos type-0 for memcpy.
>>
>> While the patch doesn't trigger any false positives (AFAIK) it is
>> subject to a fair number of false negatives due to the limitations
>> of the tree-object-size pass, and due to transformations done by
>> other passes that prevent it from detecting some otherwise obvious
>> overflows.  Although unfortunate, I believe the warnings that are
>> emitted are useful as the first line of defense in software that
>> doesn't use _FORTIFY_SOURCE (such as GCC itself).   And this can
>> of course be improved if some of the limitations are removed over
>> time.
>>
>> Martin
>