Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 24 May 2019 10:32:22 +0800
From:   Gen Zhang <blackgod016574@gmail.com>
To:     maarten.lankhorst@linux.intel.com, maxime.ripard@bootlin.com
Cc:     jani.nikula@linux.intel.com, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] drm_edid-load: Fix a missing-check bug in
 drm_load_edid_firmware()
Message-ID: <20190524023222.GA5302@zhanggen-UX430UQ>
References: <20190522123920.GB6772@zhanggen-UX430UQ>
 <87o93u7d3s.fsf@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87o93u7d3s.fsf@intel.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In drm_load_edid_firmware(), fwstr is allocated by kstrdup(). And fwstr
is dereferenced in the following codes. However, memory allocation 
functions such as kstrdup() may fail and returns NULL. Dereferencing 
this null pointer may cause the kernel go wrong. Thus we should check 
this kstrdup() operation.
Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to
the caller site.

Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
---
diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
index a491509..a0e107a 100644
--- a/drivers/gpu/drm/drm_edid_load.c
+++ b/drivers/gpu/drm/drm_edid_load.c
@@ -290,6 +290,8 @@ struct edid *drm_load_edid_firmware(struct drm_connector *connector)
 	 * the last one found one as a fallback.
 	 */
 	fwstr = kstrdup(edid_firmware, GFP_KERNEL);
+	if (!fwstr)
+		return ERR_PTR(-ENOMEM);
 	edidstr = fwstr;
 
 	while ((edidname = strsep(&edidstr, ","))) {
---