The Linux Kernel Mailing List
 help / color / mirror / Atom feed
From: Thorsten Blum <thorsten.blum@linux.dev>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND 1/2] x86/boot: validate earlyprintk= baud rate
Date: Fri, 15 May 2026 12:47:50 +0200	[thread overview]
Message-ID: <agb51om47Vu_kVnv@linux.dev> (raw)
In-Reply-To: <a2ab80f3-2887-499c-951b-1b587ea58b2b@intel.com>

Hi Dave,

On Wed, May 13, 2026 at 10:05:30AM -0700, Dave Hansen wrote:
> > Values greater than BASE_BAUD would produce divisor 0, and
> > baud 1 would produce divisor BASE_BAUD, which exceeds 16 bits.
> 
> My inclination would be to leave this code as simple as possible. If
> users screw up a baud rate, they'll get no output and have to go fix it.
> 
> Why does this need to be robust against bad user input?

OK, I guess any baud rate that doesn't crash or hang the system is
acceptable. Let's drop patch 1/2 then and I'll resend patch 2/2 as a
standalone patch.

I've also sent another patch yesterday that prevents the same division
by zero and thus early boot hang in early_serial_init() when using
console=uart8250:

https://lore.kernel.org/lkml/20260514143014.516303-3-thorsten.blum@linux.dev/

Thanks,
Thorsten

      reply	other threads:[~2026-05-15 10:47 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-13 16:48 [PATCH RESEND 1/2] x86/boot: validate earlyprintk= baud rate Thorsten Blum
2026-05-13 16:48 ` [PATCH RESEND 2/2] x86/boot: use BASE_BAUD and DEFAULT_SERIAL_PORT Thorsten Blum
2026-05-13 17:05 ` [PATCH RESEND 1/2] x86/boot: validate earlyprintk= baud rate Dave Hansen
2026-05-15 10:47   ` Thorsten Blum [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=agb51om47Vu_kVnv@linux.dev \
    --to=thorsten.blum@linux.dev \
    --cc=bp@alien8.de \
    --cc=dave.hansen@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=tglx@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox