linux-kernel - Re: [PATCH v7] firmware: google: Implement cbmem in sysfs driver

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: <Yu7TGDYTyzFLoVe4@chromium.org>
Date:   Sat, 6 Aug 2022 13:46:16 -0700
From:   Jack Rosenthal <jrosenth@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Tzung-Bi Shih <tzungbi@...nel.org>,
        Guenter Roeck <groeck@...omium.org>,
        Julius Werner <jwerner@...omium.org>
Subject: Re: [PATCH v7] firmware: google: Implement cbmem in sysfs driver

On 2022-08-04 at 15:59 -0500, Stephen Boyd wrote:
> I suspect this won't work because the driver can be unbound, and thus
> the mapping can be destroyed by devm, but then the kobject and sysfs
> file like 'mem' can be held by userspace after the driver is unbound.
> Userspace access after that time will try to read/write unmapped memory.

When the driver is unbound, read()/write() will return -ENODEV, and
mmap() isn't supported.

> Why not make this in the bus driver (coreboot-table.c)? In fact, most
> things could probably be created there instead of in a 'driver' that
> really isn't doing much 'driving' at all.

In v8, I moved the coreboot_kobj to coreboot-table.c.  I imagine in the
future we could move some of the other things (e.g., "vpd") under this
object for consistency.  So now the structure is:

   /sys/firmware/coreboot/cbmem/<id>/...