linux-kernel - Re: [PATCH] wifi: rt2x00: use explicitly signed type for clamping

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Y08SGz/xGSN87ynk@zx2c4.com>
Date:   Tue, 18 Oct 2022 14:52:43 -0600
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Stanislaw Gruszka <stf_xl@...pl>,
        Helmut Schaa <helmut.schaa@...glemail.com>,
        Kalle Valo <kvalo@...nel.org>
Subject: Re: [PATCH] wifi: rt2x00: use explicitly signed type for clamping

On Tue, Oct 18, 2022 at 11:40:54PM +0300, Andy Shevchenko wrote:
> On Tue, Oct 18, 2022 at 02:27:34PM -0600, Jason A. Donenfeld wrote:
> > On some platforms, `char` is unsigned, which makes casting -7 to char
> > overflow, which in turn makes the clamping operation bogus. Instead,
> > deal with an explicit `s8` type, so that the comparison is always
> > signed, and return an s8 result from the function as well. Note that
> > this function's result is assigned to a `short`, which is always signed.
> 
> Why not to use short? See my patch I just sent.

Trying to have the most minimal change here that doesn't rock the boat.
I'm not out to rewrite the driver. I don't know the original author's
rationales. This patch here is correct and will generate the same code
as before on architectures where it wasn't broken.

However, if you want your "change the codegen" patch to be taken
seriously, you should probably send it to the wireless maintainers like
this one, and they can decide. Personally, I don't really care either
way.

Jason