Re: [PATCH v2] kbuild: treat char as always unsigned

From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-toolchains@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2] kbuild: treat char as always unsigned
Date: Mon, 24 Oct 2022 10:10:53 -0700	[thread overview]
Message-ID: <CAHk-=wgK3Vs+7Kor-SisRHJYzV1tXD+=D4+W1XkfHOV2KN_OGw@mail.gmail.com> (raw)
In-Reply-To: <Y1a+cHkFt54gJv54@zx2c4.com>

On Mon, Oct 24, 2022 at 9:34 AM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> Give these a minute to hit Lore, but patches just submitted to various
> maintainers as fixes (for 6.1), since these are already broken on some
> architecture.

Hold up a minute.

Some of those may need more thought. For example, that first one:

> https://lore.kernel.org/all/20221024163005.536097-1-Jason@zx2c4.com

looks just *strange*. As far as I can tell, no other wireless drivers
do any sign checks at all.

Now, I didn't really look around a lot, but looking at a few other
SIOCSIWESSID users, most don't even seem to treat it as a string at
all, but as just a byte dump (so memcpy() instead of strncpy())

As far as I know, there are no actual rules for SSID character sets,
and while using utf-8 or something else might cause interoperability
problems, this driver seems to be just confused. If you want to check
for "printable characters", that check is still wrong.

So I don't think this is a "assume char is signed" issue. I think this
is a "driver is confused" issue.

IOW, I don't think these are 6.1 material as some kind of obvious
fixes, at least not without driver author acks.

                Linus