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From: Bill Wendling <morbo@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Bill Wendling <isanbard@gmail.com>,
	Tony Luck <tony.luck@intel.com>,  Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	 Dave Hansen <dave.hansen@linux.intel.com>,
	 "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Phillip Potter <phil@philpotter.co.uk>,
	 Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	 "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Jan Kara <jack@suse.com>,
	 Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	 Florian Westphal <fw@strlen.de>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	 Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>, Jaroslav Kysela <perex@perex.cz>,
	 Takashi Iwai <tiwai@suse.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>,
	 Ross Philipson <ross.philipson@oracle.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	 linux-edac@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	 ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	linux-mm@kvack.org,  netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org,  Networking <netdev@vger.kernel.org>,
	alsa-devel@alsa-project.org,
	 clang-built-linux <llvm@lists.linux.dev>
Subject: Re: [PATCH 00/12] Clang -Wformat warning fixes
Date: Thu, 9 Jun 2022 15:49:21 -0700	[thread overview]
Message-ID: <CAGG=3QXDt9AeCQOAp1311POFRSByJru4=Q=oFiQn3u2iZYk2_w@mail.gmail.com> (raw)
In-Reply-To: <20220609152527.4ad7862d4126e276e6f76315@linux-foundation.org>

On Thu, Jun 9, 2022 at 3:25 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Thu,  9 Jun 2022 22:16:19 +0000 Bill Wendling <morbo@google.com> wrote:
>
> > This patch set fixes some clang warnings when -Wformat is enabled.
> >
>
> tldr:
>
> -       printk(msg);
> +       printk("%s", msg);
>
> the only reason to make this change is where `msg' could contain a `%'.
> Generally, it came from userspace.

It helps kernel developers not accidentally to insert an unescaped '%'
in their messages, potentially exposing their code to an attack
vector.

> Otherwise these changes are a
> useless consumer of runtime resources.

Calling a "printf" style function is already insanely expensive. :-) I
understand that it's not okay blithely to increase runtime resources
simply because it's already slow, but in this case it's worthwhile.

> I think it would be better to quieten clang in some fashion.

The "printk" and similar functions all have the "__printf" attribute.
I don't know of a modification to that attribute which can turn off
this type of check.

-bw


  reply	other threads:[~2022-06-09 22:49 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-09 22:16 Bill Wendling
2022-06-09 22:16 ` [PATCH 01/12] x86/mce: use correct format characters Bill Wendling
2022-06-09 23:14   ` Randy Dunlap
2022-06-09 23:18     ` Bill Wendling
2022-06-09 22:16 ` [PATCH 02/12] x86/CPU/AMD: " Bill Wendling
2022-06-09 22:16 ` [PATCH 03/12] x86/e820: " Bill Wendling
2022-06-09 22:16 ` [PATCH 04/12] blk-cgroup: " Bill Wendling
2022-06-10  8:10   ` Christoph Hellwig
2022-06-09 22:16 ` [PATCH 05/12] fs: quota: " Bill Wendling
2022-06-09 22:16 ` [PATCH 06/12] PNP: " Bill Wendling
2022-06-09 22:16 ` [PATCH 07/12] driver/char: " Bill Wendling
2022-06-10  5:18   ` Greg Kroah-Hartman
2022-06-13 18:40     ` Bill Wendling
2022-06-09 22:16 ` [PATCH 08/12] cdrom: " Bill Wendling
2022-06-12 16:23   ` Phillip Potter
2022-06-13 18:47     ` Bill Wendling
2022-06-09 22:16 ` [PATCH 09/12] ALSA: seq: " Bill Wendling
2022-06-09 22:16 ` [PATCH 10/12] " Bill Wendling
2022-06-09 22:16 ` [PATCH 11/12] ALSA: control: " Bill Wendling
2022-06-09 22:16 ` [PATCH 12/12] netfilter: conntrack: " Bill Wendling
2022-07-11 14:35   ` Pablo Neira Ayuso
2022-06-09 22:25 ` [PATCH 00/12] Clang -Wformat warning fixes Andrew Morton
2022-06-09 22:49   ` Bill Wendling [this message]
2022-06-09 23:03     ` Jan Engelhardt
2022-06-09 23:16       ` Bill Wendling
2022-06-10  1:19         ` Andrew Morton
2022-06-10  5:20         ` Greg Kroah-Hartman
2022-06-10 12:44           ` Joe Perches
2022-06-10  8:17     ` David Laight
2022-06-10  8:32       ` Jan Engelhardt
2022-06-10  9:14         ` David Laight
2022-06-10  9:22           ` Jan Engelhardt
2022-06-10  0:32   ` Nick Desaulniers

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