linux-kernel - Re: [PATCH] drm/virtio: Fix GEM handle creation UAF

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Message-ID: <CAPaKu7Ti5sEzGVRaE8UFx1RRbBba3=am8rwZf3totX1z8bfJHQ@mail.gmail.com>
Date:   Fri, 16 Dec 2022 15:50:22 -0800
From:   Chia-I Wu <olvaffe@...il.com>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        David Airlie <airlied@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/virtio: Fix GEM handle creation UAF

On Fri, Dec 16, 2022 at 3:33 PM Rob Clark <robdclark@...il.com> wrote:
>
> From: Rob Clark <robdclark@...omium.org>
>
> Userspace can guess the handle value and try to race GEM object creation
> with handle close, resulting in a use-after-free if we dereference the
> object after dropping the handle's reference.  For that reason, dropping
> the handle's reference must be done *after* we are done dereferencing
> the object.
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
Reviewed-by: Chia-I Wu <olvaffe@...il.com>