linux-kernel - Re: [PATCH] drm/qxl: fix null pointer dereference in qxl_add

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Message-ID: <7efdcd35-7511-491a-a0b2-c500ebb2256d@web.de>
Date: Wed, 26 Jun 2024 14:18:06 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: Ma Ke <make24@...as.ac.cn>, dri-devel@...ts.freedesktop.org,
 spice-devel@...ts.freedesktop.org, virtualization@...ts.linux.dev,
 Daniel Vetter <daniel@...ll.ch>, Dave Airlie <airlied@...hat.com>,
 Gerd Hoffmann <kraxel@...hat.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>
Cc: LKML <linux-kernel@...r.kernel.org>, David Airlie <airlied@...il.com>
Subject: Re: [PATCH] drm/qxl: fix null pointer dereference in qxl_add_mode

> In qxl_add_mode(), the return value of drm_cvt_mode() is assigned to mode,
> which will lead to a possible NULL pointer dereference on failure of
> drm_cvt_mode(). 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_cvt_mode” failed. This pointer was used
   in subsequent statements 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” and “Cc”) accordingly?

3. How do you think about to append parentheses to the function name
   in the summary phrase?

Regards,
Markus