linux-kernel - Re: [PATCH 2/2] arm/mm : Report actual image regions in /proc/iomem

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 for Android: free password hash cracker in your pocket

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

Date:   Mon, 6 Mar 2023 12:28:36 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Jungseung Lee <js07.lee@...sung.com>
Cc:     linus.walleij@...aro.org, amit.kachhap@....com, ardb@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        keescook@...omium.org, js07.lee@...il.com
Subject: Re: [PATCH 2/2] arm/mm : Report actual image regions in /proc/iomem

On Mon, Mar 06, 2023 at 09:14:23PM +0900, Jungseung Lee wrote:
> Hi, Russell
> 
> > -----Original Message-----
> > From: Russell King (Oracle) <linux@...linux.org.uk>
> > Sent: Monday, March 6, 2023 8:10 PM
> > To: Jungseung Lee <js07.lee@...sung.com>
> > Cc: linus.walleij@...aro.org; amit.kachhap@....com; ardb@...nel.org;
> > linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org;
> > keescook@...omium.org; js07.lee@...il.com
> > Subject: Re: [PATCH 2/2] arm/mm : Report actual image regions in
> > /proc/iomem
> > 
> > On Mon, Mar 06, 2023 at 02:51:55PM +0900, Jungseung Lee wrote:
> > >  The resource reservations in /proc/iomem made for the kernel image
> > > did  not reflect the gaps between text, rodata, and data.
> > >  Add the "rodata" resource and update the start/end calculations.
> > >
> > >  Before :
> > > 04000000-2f7fffff : System RAM
> > >   04100000-04cfffff : Kernel code
> > >   04e00000-05369a27 : Kernel data
> > >
> > >  After :
> > > 04000000-2f7fffff : System RAM
> > >   04100000-049fffff : Kernel code
> > >   04a00000-04cb2fff : Kernel rodata
> > >   04e00000-05369a27 : Kernel data
> > 
> > NAK. This is API, and programs do read and parse this file. It is
> > important that this file reports these parameters in a similar way to
> > other architectures. Other architectures do not split up the
> > individual regions.
> > 
> 
> Sounds like an important point, but I failed to find which programs use it
> as an API. Could you tell me which program uses it as an API?
> 
> In fact, x86 architecture also split up the individual regions in this way.
> In addition, most architectures separate the "Kernel bss" area, but arm does
> not.

Take a look at kexec-tools - that certainly does parse /proc/iomem
looking for entries such as "Kernel code" and "Kernel data".

It's fine for an architecture to decide to do something else if it
started to do it early on, but not when something has been established
for decades.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!