linux-kernel - [PATCH] video: fbdev: fix possible null dereference

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Message-Id: <1423756056-15108-1-git-send-email-sudipm.mukherjee@gmail.com>
Date:	Thu, 12 Feb 2015 21:17:36 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>
Cc:	Sudip Mukherjee <sudipm.mukherjee@...il.com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] video: fbdev: fix possible null dereference

we were dereferencing edid first and the NULL check was after
accessing that. now we are using edid only if we know that
it is not NULL.

Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---
 drivers/video/fbdev/core/fbmon.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/core/fbmon.c b/drivers/video/fbdev/core/fbmon.c
index 9533859..868facd 100644
--- a/drivers/video/fbdev/core/fbmon.c
+++ b/drivers/video/fbdev/core/fbmon.c
@@ -624,9 +624,6 @@ static struct fb_videomode *fb_create_modedb(unsigned char *edid, int *dbsize,
 	int num = 0, i, first = 1;
 	int ver, rev;
 
-	ver = edid[EDID_STRUCT_VERSION];
-	rev = edid[EDID_STRUCT_REVISION];
-
 	mode = kzalloc(50 * sizeof(struct fb_videomode), GFP_KERNEL);
 	if (mode == NULL)
 		return NULL;
@@ -637,6 +634,9 @@ static struct fb_videomode *fb_create_modedb(unsigned char *edid, int *dbsize,
 		return NULL;
 	}
 
+	ver = edid[EDID_STRUCT_VERSION];
+	rev = edid[EDID_STRUCT_REVISION];
+
 	*dbsize = 0;
 
 	DPRINTK("   Detailed Timings\n");
-- 
1.8.1.2

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