linux-kernel - Re: [PATCH] drm/gma500: fix a possible null pointer dereference

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Message-ID: <22810fcc-4de8-4f2e-886a-6af83195028c@web.de>
Date: Sat, 22 Jun 2024 17:08:36 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: Ma Ke <make24@...as.ac.cn>, dri-devel@...ts.freedesktop.org,
 Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>,
 Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
 Thomas Zimmermann <tzimmermann@...e.de>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/gma500: fix a possible null pointer dereference

> In cdv_intel_lvds_get_modes(), the return value of drm_mode_duplicate()
> is assigned to mode, which will lead to a NULL pointer dereference on
> failure of drm_mode_duplicate(). Add a check to avoid npd.

1. Can a wording approach (like the following) be a better change description?

   A null pointer is stored in the local variable “mode” after a call
   of the function “drm_mode_duplicate” failed. This pointer was passed to
   a subsequent call of the function “drm_mode_probed_add” where an undesirable
   dereference will be performed then.
   Thus add a corresponding return value check.

2. Would you like to add any tags (like “Fixes”) accordingly?

3. How do you think about to use a summary phrase like “Avoid null pointer dereference
   in cdv_intel_lvds_get_modes()”?

Regards,
Markus