linux-kernel - Re: [PATCH 0/4] Add tooling to disable debugfs on OMAP based systems

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: <20251129153644.333498f1@kemnade.info>
Date: Sat, 29 Nov 2025 15:36:44 +0100
From: Andreas Kemnade <andreas@...nade.info>
To: Richard Weinberger <richard@....at>
Cc: linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
 devicetree@...r.kernel.org, arnd@...db.de, lee@...nel.org, dakr@...nel.org,
 rafael@...nel.org, gregkh@...uxfoundation.org, broonie@...nel.org,
 tony@...mide.com, rogerq@...nel.org, khilman@...libre.com,
 aaro.koskinen@....fi, conor+dt@...nel.org, krzk+dt@...nel.org,
 robh@...nel.org
Subject: Re: [PATCH 0/4] Add tooling to disable debugfs on OMAP based
 systems

On Sat, 29 Nov 2025 15:20:38 +0100
Richard Weinberger <richard@....at> wrote:

> It came to my attention that commands such as `grep -r / -e ...` can cause
> crashes on an AM572x based system.
> An investigation found that reading from various files in /sys/kernel/debug/regmap
> causes imprecise async data aborts.
> 
> One of these register maps is the CTRL_MODULE_CORE register map at 0x4A002000.
> It contains various registers marked as reserved, but the manual indicates
> that read access is still allowed.
> On said system, reading from most registers seems to work, but for some
> an async data abort happens. So it's not entirely clear what registers are safe
> and which are not.
> 
it is usually not about individual registers, but about accessing 
unpowered devices/modules,

so it is probably more the logic like:

if (pm_runtime_is_suspended(regmap->device))
	-EACCESS;

Try to play around with on >power/control in sysfs.

> So, add tooling to allow disabling debugfs access to such dangerous registers.
> Splitting the register map definitions in the device tree seemed less practical to
> me since it would unnecessarily make the device trees more complicated.
> 
So is it really a description of the hardware? Maybe there are some special
cases, too.

Regards,
Andreas