linux-kernel - Re: Re: [PATCH] ARM: Fix support for CMDLINE

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: <Z-qQuyG7rDeSF_oX@shell.armlinux.org.uk>
Date: Mon, 31 Mar 2025 13:55:23 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: 谢致邦 (XIE Zhibang) <Yeking@...54.com>
Cc: ardb@...nel.org, bjorn.andersson@...yericsson.com, dave@...ilevsky.ca,
	ebiggers@...gle.com, linus.walleij@...aro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	liuyuntao12@...wei.com, lumag@...nel.org, masahiroy@...nel.org,
	nathan@...nel.org, nico@...xnic.net, oskar.andero@...yericsson.com,
	ruanjinjie@...wei.com, victor.boivie@...yericsson.com
Subject: Re: Re: [PATCH] ARM: Fix support for CMDLINE_EXTEND

On Mon, Mar 31, 2025 at 08:29:21AM +0000, 谢致邦 (XIE Zhibang) wrote:
> > Later arguments override earlier arguments. Any compiled-in command line
> > needs to be overridable by user supplied input from the boot loader. The
> > current behaviour is correct.
> 
> CMDLINE_EXTEND is for the built-in command line to "Extend bootloader kernel
> arguments", not for the bootloader command line to extend/override built-in
> command line.
> 
> Don't forget that the default empty CMDLINE already gives the bootloader the
> ability to override everything. Not to mention that even if CMDLINE is not
> empty, the default CMDLINE_FROM_BOOTLOADER continues to give the bootloader the
> ability to override all.

The help text:

+         The command-line arguments provided by the boot loader will be
+         appended to the default kernel command string.

so, you end up with default kernel command string _followed by_ the
boot loader arguments. This allows the boot loader arguments to
override anything that is in the default kernel command string.
That's why it is a _default_ - it can be overrided.

If the boot loader command string is extended by the default kernel
command string, then that doesn't happen.

CMDLINE_EXTEND is default _followed by_ boot loader.

You're wanting it to be the other way around. That's broken.

No.

Sorry.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!