linux-kernel - Re: [PATCH 2/2] mm/usercopy: enable usercopy size checking for modern versions of gcc

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Message-ID: <CA+55aFxfE3_n08XPqys3j6PxcSfn=Mds1v-SXjO9umWnjsQN7A@mail.gmail.com>
Date:   Mon, 29 Aug 2016 08:36:46 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Byungchul Park <byungchul.park@....com>,
        Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH 2/2] mm/usercopy: enable usercopy size checking for modern
 versions of gcc

On Mon, Aug 29, 2016 at 7:48 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
>
> So I *think* your patch fixes the wrong problem.  That's probably at
> least somewhat my fault because I misunderstood the issue before and may
> have described it wrong at some point.
>
> AFAICT, gcc isn't doing anything wrong, and the false positives are
> "intentional".
>
> There are in fact two static warnings (which are being silenced for new
> versions of gcc):

[ snip snip details ]

Ok.

Color me convinced, I never even looked at the two different cases, I
thought it was just one issue.

Let's just remove the spurious false positive warning then, in order
to re-instate the *actual* warning that right now is disabled entirely
due to the unrelated false positives.

Thanks for looking into this. Would you happen to also have a patch
that can be applied? Hint hint..

               Linus