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: Mon, 6 May 2024 09:29:36 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Sean Anderson <sean.anderson@...ux.dev>, 
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Michal Simek <michal.simek@....com>, 
	dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [BUG] drm: zynqmp_dp: Lockup in zynqmp_dp_bridge_detect when
 device is unbound

Hi Laurent, Sean,

On Sat, May 04, 2024 at 03:21:18PM GMT, Laurent Pinchart wrote:
> On Fri, May 03, 2024 at 05:54:32PM -0400, Sean Anderson wrote:
> > I have discovered a bug in the displayport driver on drm-misc-next. To
> > trigger it, run
> > 
> > echo fd4a0000.display > /sys/bus/platform/drivers/zynqmp-dpsub/unbind
> > 
> > The system will become unresponsive and (after a bit) splat with a hard
> > LOCKUP. One core will be unresponsive at the first zynqmp_dp_read in
> > zynqmp_dp_bridge_detect.
> > 
> > I believe the issue is due the registers being unmapped and the block
> > put into reset in zynqmp_dp_remove instead of zynqmp_dpsub_release.
> 
> That is on purpose. Drivers are not allowed to access the device at all
> after .remove() returns.

It's not "on purpose" no. Drivers indeed are not allowed to access the
device after remove, but the kernel shouldn't crash. This is exactly
why we have drm_dev_enter / drm_dev_exit.

Maxime

Download attachment "signature.asc" of type "application/pgp-signature" (274 bytes)

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ