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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 16 Mar 2018 13:14:17 -0700
Message-ID: <CA+55aFxLpdfyfTqhkHQoedQuqTcLRw3bYOgyz1s0eRW6cBmFTA@mail.gmail.com>
Subject: Re: [PATCH v5 0/2] Remove false-positive VLAs when using max()
To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Florian Weimer <fweimer@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Randy Dunlap <rdunlap@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        David Laight <David.Laight@aculab.com>,
        Ian Abbott <abbotti@mev.co.uk>,
        linux-input <linux-input@vger.kernel.org>,
        linux-btrfs <linux-btrfs@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>
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On Fri, Mar 16, 2018 at 1:03 PM, Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>>
>> Kees - is there some online "gcc-4.4 checker" somewhere? This does
>> seem to work with my gcc. I actually tested some of those files you
>> pointed at now.
>
> I use this one:
>
>   https://godbolt.org/

Well, my *test* code works on that one and -Wvla -Werror.

It does not work with gcc-4.1.x, but works with gcc-4.4.x.

I can't seem to see the errors any way, I wonder if
__builtin_choose_expr() simply didn't exist back then.

Odd that you can't view warnings/errors with it.

But it's possible that it fails on more complex stuff in the kernel.

I've done a "allmodconfig" build with that patch, and the only issue
it found was that (real) type issue in tpm_tis_core.h.

                Linus