Re: [PATCH] yam: avoid null pointer dereference error

[Colin Ian King <colin.king@canonical.com>]

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On 27/03/13 17:46, David Miller wrote:
> From: Ben Hutchings <bhutchings@solarflare.com>
> Date: Wed, 27 Mar 2013 17:44:17 +0000
>
>> On Wed, 2013-03-27 at 11:19 +0000, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> yam_open checks if dev is null, however, before that check it
>>> accesses some of the fields from dev in a proceeding printk which
>>> will cause a null pointer dereference error if dev is nul. Move
>>> the printk to after the null check.
>>
>> This function will never be called with dev == NULL.
>
> Then let's remove at least that part of the check.
>
Good point. How about the following..



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From 564f111f196d9d7293e922a68ba973210d191129 Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king@canonical.com>
Date: Wed, 27 Mar 2013 13:59:05 -0400
Subject: [PATCH] yam: remove redundant null check on dev

yam_open has a redundant null check on null,  it will
never be called with dev == NULL. Remove this redundant check.
This also cleans up a smatch warning:

drivers/net/hamradio/yam.c:869 yam_open() warn: variable
  dereferenced before check 'dev' (see line 867)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/hamradio/yam.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 4cf8f10..b2d863f 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -866,7 +866,7 @@ static int yam_open(struct net_device *dev)
 
 	printk(KERN_INFO "Trying %s at iobase 0x%lx irq %u\n", dev->name, dev->base_addr, dev->irq);
 
-	if (!dev || !yp->bitrate)
+	if (!yp->bitrate)
 		return -ENXIO;
 	if (!dev->base_addr || dev->base_addr > 0x1000 - YAM_EXTENT ||
 		dev->irq < 2 || dev->irq > 15) {
-- 
1.7.9.5