linux-kernel - [PATCH] security: avoid calling a NULL function pointer in drivers/video/tvaudio.c

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Date:	Fri, 10 Oct 2008 21:18:36 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	mchehab@...radead.org, torvalds@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, security@...r.kernel.org
Subject: [PATCH] security: avoid calling a NULL function pointer in
 drivers/video/tvaudio.c


From: Arjan van de Ven <arjan@...ux.intel.com>
Date: Fri, 10 Oct 2008 21:16:12 -0700
Subject: [PATCH] security: avoid calling a NULL function pointer in drivers/video/tvaudio.c

NULL function pointers are very bad security wise. This one got caught by
kerneloops.org quite a few times, so it's happening in the field....

Fix is simple, check the function pointer for NULL, like 6 other places
in the same function are already doing.

Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
---
 drivers/media/video/tvaudio.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/tvaudio.c b/drivers/media/video/tvaudio.c
index 463680b..b59e472 100644
--- a/drivers/media/video/tvaudio.c
+++ b/drivers/media/video/tvaudio.c
@@ -1792,7 +1792,7 @@ static int chip_command(struct i2c_client *client,
 		break;
 	case VIDIOC_S_FREQUENCY:
 		chip->mode = 0; /* automatic */
-		if (desc->checkmode) {
+		if (desc->checkmode && desc->setmode) {
 			desc->setmode(chip,V4L2_TUNER_MODE_MONO);
 			if (chip->prevmode != V4L2_TUNER_MODE_MONO)
 				chip->prevmode = -1; /* reset previous mode */
-- 
1.5.5.1



-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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