linux-kernel - Re: [PATCH v2 0/3] drm/nouveau: fix a use-after-free in postclose()

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Message-ID: <b4da382b17a77b66e45fd374c9d806dac6054e3a.camel@redhat.com>
Date:   Fri, 26 Mar 2021 18:00:51 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     Jeremy Cline <jcline@...hat.com>, Ben Skeggs <bskeggs@...hat.com>
Cc:     Karol Herbst <kherbst@...hat.com>, David Airlie <airlied@...ux.ie>,
        nouveau@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] drm/nouveau: fix a use-after-free in postclose()

This patch series is:

Reviewed-by: Lyude Paul <lyude@...hat.com>

Btw - in the future if you need to send a respin of multiple patches, you need
to send it as it's own separate series instead of replying to the previous one
(one-off respins can just be posted as replies though), otherwise patchwork
won't pick it up

On Wed, 2020-11-25 at 15:26 -0500, Jeremy Cline wrote:
> This series fixes a number of use-after-frees in nouveau's postclose()
> handler. It was discovered by pointing IGT's core_hotunplug tests at a
> nouveau device, but the steps to reproduce it are simple:
> 
> 1. Open the device file
> 2. Unbind the driver or remove the device
> 3. Close the file opened in step 1.
> 
> During the device removal, the nouveau_drm structure is de-allocated,
> but is dereferenced in the postclose() handler.
> 
> One obvious solution is to ensure all the operations in the postclose()
> handler are valid by extending the lifetime of the nouveau_drm
> structure. This is possible with the new devm_drm_dev_alloc() interface,
> but the change is somewhat invasive so I thought it best to submit that
> work separately.
> 
> Instead, we make use of the drm_dev_unplug() API, clean up all clients
> in the device removal call, and check to make sure the device has not
> been unplugged in the postclose() handler. While this does not enable
> hot-unplug support for nouveau, it's enough to avoid crashing the kernel
> and leads to all the core_hotunplug tests to pass.
> 
> This series reroll addresses a missing mutex_destroy() call and a typo
> in a commit message.
> 
> Jeremy Cline (3):
>   drm/nouveau: use drm_dev_unplug() during device removal
>   drm/nouveau: Add a dedicated mutex for the clients list
>   drm/nouveau: clean up all clients on device removal
> 
>  drivers/gpu/drm/nouveau/nouveau_drm.c | 42 +++++++++++++++++++++++----
>  drivers/gpu/drm/nouveau/nouveau_drv.h |  5 ++++
>  2 files changed, 42 insertions(+), 5 deletions(-)
> 

-- 
Sincerely,
   Lyude Paul (she/her)
   Software Engineer at Red Hat
   
Note: I deal with a lot of emails and have a lot of bugs on my plate. If you've
asked me a question, are waiting for a review/merge on a patch, etc. and I
haven't responded in a while, please feel free to send me another email to check
on my status. I don't bite!