linux-kernel - [PATCH v2 0/2] drm: A couple of fixes for drm_copy

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Message-Id: <20220705100215.572498-1-javierm@redhat.com>
Date:   Tue,  5 Jul 2022 12:02:12 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Peter Robinson <pbrobinson@...il.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH v2 0/2] drm: A couple of fixes for drm_copy_field() helper function

Hello,

Peter Robinson reported me a kernel bug in one of his aarch64 test boards
and even though I was not able to reproduce it, I think that figured out
what the problem was. It seems the cause is that a DRM driver doesn't set
some of the struct drm fields copied to userspace via DRM_IOCTL_VERSION.

Even though this is a driver bug, we can make drm_copy_field() more robust
and warn about it instead of leading to an attempt to copy a NULL pointer.

While looking at this, I also found that a variable in drm_copy_field() is
not using the correct type. So I included that change in the patch-set too.

Best regards,
Javier

Changes in v2:
- Add Peter Robinson Tested-by and Thomas Zimmermann Reviewed-by tags.
- Just warn if a value isn't set and report it as a string of length 0.
  (Thomas Zimmermann).

Javier Martinez Canillas (2):
  drm: Use size_t type for len variable in drm_copy_field()
  drm: Prevent drm_copy_field() to attempt copying a NULL pointer

 drivers/gpu/drm/drm_ioctl.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

-- 
2.36.1