linux-kernel - Re: [PATCHv4]Checks for Null value in function *get

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Message-ID: <CAPDOMVh4iBhWe50LZtiotpgWBn3fhX1jofyeAeYW4kHxx+Q4FQ@mail.gmail.com>
Date:	Mon, 16 Jun 2014 11:45:01 -0400
From:	Nick Krause <xerofoify@...il.com>
To:	Steve Wise <swise@...ngridcomputing.com>
Cc:	swise@...lsio.com, roland@...nel.org, sean.hefty@...el.com,
	hal.rosenstock@...il.com, linux-rdma@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4]Checks for Null value in function *get_skub

Can we close this bug or is it still a issue as we can'
return NULL from kfree or kfree_skb. Here is the bug
ID 44631 I would close it if we are done with the bug
otherwise I think there are no other issues with
allocating a skb,
Cheers Nick

On Mon, Jun 16, 2014 at 11:37 AM, Nick Krause <xerofoify@...il.com> wrote:
> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> ---
>  drivers/infiniband/hw/cxgb4/
> cm.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
> index f9477e2..2d56983 100644
> --- a/drivers/infiniband/hw/cxgb4/cm.c
> +++ b/drivers/infiniband/hw/cxgb4/cm.c
> @@ -340,15 +340,13 @@ static int status2errno(int status)
>   */
>  static struct sk_buff *get_skb(struct sk_buff *skb, int len, gfp_t gfp)
>  {
>  if (skb && !skb_is_nonlinear(skb) && !skb_cloned(skb)) {
>                 skb_trim(skb, 0);
>                 skb_get(skb);
>                 skb_reset_transport_header(skb);
>         } else {
> +               if (skb)
> /* NULL is ignored */.
> +                       kfree_skb (skb);
>                 skb = alloc_skb(len, gfp);
>         }
>         t4_set_arp_err_handler(skb, NULL, NULL);
>
> On Mon, Jun 16, 2014 at 11:30 AM, Steve Wise
> <swise@...ngridcomputing.com> wrote:
>> On 6/16/2014 10:25 AM, Nicholas Krause wrote:
>>>
>>> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
>>> ---
>>>   drivers/infiniband/hw/cxgb4/cm.c | 8 +++-----
>>>   1 file changed, 3 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/hw/cxgb4/cm.c
>>> b/drivers/infiniband/hw/cxgb4/cm.c
>>> index f9477e2..2d56983 100644
>>> --- a/drivers/infiniband/hw/cxgb4/cm.c
>>> +++ b/drivers/infiniband/hw/cxgb4/cm.c
>>> @@ -340,15 +340,13 @@ static int status2errno(int status)
>>>    */
>>>   static struct sk_buff *get_skb(struct sk_buff *skb, int len, gfp_t gfp)
>>>   {
>>>   if (skb && !skb_is_nonlinear(skb) && !skb_cloned(skb)) {
>>>                  skb_trim(skb, 0);
>>>                  skb_get(skb);
>>>                  skb_reset_transport_header(skb);
>>>         } else {
>>> +               if (skb)
>>> +                       kfree_skb (skb);
>>>                 skb = alloc_skb(len, gfp);
>>>         }
>>>         t4_set_arp_err_handler(skb, NULL, NULL);
>>
>>
>> Can you change the comment?  This patch is now fixing a potential skb leak.
>> Also, kfree_sb() will ignore NULL ptrs, so we could just always call it.
>> But I'd add a comment like /* NULL is ignored */.
>>
>> Thanks,
>>
>> Steve.
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