linux-kernel - Re: [PATCH v2] regmap: debugfs: Free debugfs

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]

Date:   Thu, 6 Jan 2022 20:05:15 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Matthias Schiffer <matthias.schiffer@...tq-group.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] regmap: debugfs: Free debugfs_name buffer after usage

On Thu, Jan 06, 2022 at 04:27:32PM -0300, Fabio Estevam wrote:
> On Thu, Jan 6, 2022 at 3:33 PM Mark Brown <broonie@...nel.org> wrote:

> > OK, but what's the logic here?  The name is getting thrown away here but

> I did more debugging and this is what I found:
> The 'debugfs: Directory 'dummy-iomuxc-gpr@...0000' with parent
> 'regmap' already present!' message
> happens since commit cffa4b2122f5 ("regmap: debugfs: Fix a memory leak
> when calling regmap_attach_dev").

Sure, but that just means that the bug with not cleaning up the
directory predates that.  

> # mount -t debugfs none /sys/kernel/debug/
> # cat /sys/kernel/debug/regmap/dummy-iomuxc-gpr@...0000/registers
> 00: 00000000
> 04: 48611005

What happens if the underlying regmap gets freed for some reason?  It
now only remembers the new name, not this old one, so it'll only know to
clean up the old name.

> As shown above, I don't see the '
> /sys/kernel/debug/regmap/20e0000.pinctrl-gpr' directory being created,
> so there is nothing to clean.

Creating that file is the behaviour you are demanding...

> Where exactly would you like me to call regmap_debugfs_exit()?

Before we try to reinitialise debugfs for the new name seems like the
obvious place.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)