[1/1] net: thunderx: avoid null pointer dereference

In function bgx_lmac_handler only use a member of
lmac after checking it is not null.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

On 05/17/2016 12:40 PM, Heinrich Schuchardt wrote:
> In function bgx_lmac_handler only use a member of
> lmac after checking it is not null.
>

Were you seeing and actual OOPs, or is this only a theoretical problem 
flagged by some sort of static code checker?

> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

In any event, it seems sane to make this change, so:

Acked-by: David Daney <david.daney@cavium.com>


> ---
>   drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> index d20539a..3ed2198 100644
> --- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> +++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
> @@ -274,12 +274,14 @@ static void bgx_sgmii_change_link_state(struct lmac *lmac)
>   static void bgx_lmac_handler(struct net_device *netdev)
>   {
>   	struct lmac *lmac = container_of(netdev, struct lmac, netdev);
> -	struct phy_device *phydev = lmac->phydev;
> +	struct phy_device *phydev;
>   	int link_changed = 0;
>
>   	if (!lmac)
>   		return;
>
> +	phydev = lmac->phydev;
> +
>   	if (!phydev->link && lmac->last_link)
>   		link_changed = -1;
>
>

On 05/17/2016 10:21 PM, David Daney wrote:
> On 05/17/2016 12:40 PM, Heinrich Schuchardt wrote:
>> In function bgx_lmac_handler only use a member of
>> lmac after checking it is not null.
>>
> 
> Were you seeing and actual OOPs, or is this only a theoretical problem
> flagged by some sort of static code checker?

Cppcheck identified the code inconsistency.

If the struct netdev * parameter cannot be NULL, you could eliminate the
check.

Other drivers do no have check against a NULL parameter in the
adjust_link handler function (e.g. bgmac_adjust_link,
pxa168_eth_adjust_link).

Best regards

Heinrich

> 
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> 
> In any event, it seems sane to make this change, so:
> 
> Acked-by: David Daney <david.daney@cavium.com>
> 
> 
>> ---
>>   drivers/net/ethernet/cavium/thunder/thunder_bgx.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
>> b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
>> index d20539a..3ed2198 100644
>> --- a/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
>> +++ b/drivers/net/ethernet/cavium/thunder/thunder_bgx.c
>> @@ -274,12 +274,14 @@ static void bgx_sgmii_change_link_state(struct
>> lmac *lmac)
>>   static void bgx_lmac_handler(struct net_device *netdev)
>>   {
>>       struct lmac *lmac = container_of(netdev, struct lmac, netdev);
>> -    struct phy_device *phydev = lmac->phydev;
>> +    struct phy_device *phydev;
>>       int link_changed = 0;
>>
>>       if (!lmac)
>>           return;
>>
>> +    phydev = lmac->phydev;
>> +
>>       if (!phydev->link && lmac->last_link)
>>           link_changed = -1;
>>
>>
> 
>

From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Tue, 17 May 2016 21:40:38 +0200

> In function bgx_lmac_handler only use a member of
> lmac after checking it is not null.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

Applied.