igb: check memory allocation failure

Message ID 20170827063951.5975-1-christophe.jaillet@wanadoo.fr
State Accepted
Delegated to: Jeff Kirsher
Headers show
Series
  • igb: check memory allocation failure
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Commit Message

Christophe JAILLET Aug. 27, 2017, 6:39 a.m.
Check memory allocation failures and return -ENOMEM in such cases, as
already done for other memory allocations in this function.

This avoids NULL pointers dereference.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Christophe JAILLET Aug. 28, 2017, 5:12 p.m. | #1
Le 28/08/2017 à 01:09, Waskiewicz Jr, Peter a écrit :
> On 8/27/17 2:42 AM, Christophe JAILLET wrote:
>> Check memory allocation failures and return -ENOMEM in such cases, as
>> already done for other memory allocations in this function.
>>
>> This avoids NULL pointers dereference.
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>>    drivers/net/ethernet/intel/igb/igb_main.c | 2 ++
>>    1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
>> index fd4a46b03cc8..837d9b46a390 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -3162,6 +3162,8 @@ static int igb_sw_init(struct igb_adapter *adapter)
>>    	/* Setup and initialize a copy of the hw vlan table array */
>>    	adapter->shadow_vfta = kcalloc(E1000_VLAN_FILTER_TBL_SIZE, sizeof(u32),
>>    				       GFP_ATOMIC);
>> +	if (!adapter->shadow_vfta)
>> +		return -ENOMEM;
> Looks reasonable to me.
>
> A larger issue though I see in this function is that if we return
> -ENOMEM here, and if we return -ENOMEM from igb_init_interrupt_scheme()
> below on failure, we leak adapter->mac_table (and adapter->shadow_vfta
> in the latter).  We should add a proper unwind to free up the memory on
> failure.
>
> -PJ
>
Hi,

in fact, there is no leak because the only caller of 'igb_sw_init()' 
(i.e. 'igb_probe()'), already frees these resources in case of error, 
see [1]

These resources are also freed  in 'igb_remove()'.

Best reagrds,
CJ

[1]: 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/net/ethernet/intel/igb/igb_main.c#n2775
Brown, Aaron F Sept. 14, 2017, 2:24 a.m. | #2
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On Behalf

> Of Christophe JAILLET

> Sent: Monday, August 28, 2017 10:13 AM

> To: Waskiewicz Jr, Peter <peter.waskiewicz.jr@intel.com>; Kirsher, Jeffrey T

> <jeffrey.t.kirsher@intel.com>

> Cc: netdev@vger.kernel.org; kernel-janitors@vger.kernel.org; intel-wired-

> lan@lists.osuosl.org; linux-kernel@vger.kernel.org

> Subject: Re: [Intel-wired-lan] [PATCH] igb: check memory allocation failure

> 

> Le 28/08/2017 à 01:09, Waskiewicz Jr, Peter a écrit :

> > On 8/27/17 2:42 AM, Christophe JAILLET wrote:

> >> Check memory allocation failures and return -ENOMEM in such cases, as

> >> already done for other memory allocations in this function.

> >>

> >> This avoids NULL pointers dereference.

> >>

> >> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

> >> ---

> >>    drivers/net/ethernet/intel/igb/igb_main.c | 2 ++

> >>    1 file changed, 2 insertions(+)

> >>


This seems to be fine from a "it does not break in testing" perspective, so...

Tested-by: Aaron Brown <aaron.f.brown@intel.com


> > -PJ

> >

> Hi,

> 

> in fact, there is no leak because the only caller of 'igb_sw_init()'

> (i.e. 'igb_probe()'), already frees these resources in case of error,

> see [1]

> 

> These resources are also freed  in 'igb_remove()'.

> 

> Best reagrds,

> CJ

> 

> [1]:

> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-

> next.git/tree/drivers/net/ethernet/intel/igb/igb_main.c#n2775


But is PJ's comment saying that it is not really necessary?  If so I tend to lean towards the don't touch it if it's not broken perspective.
Waskiewicz Jr, Peter Sept. 14, 2017, 2:47 p.m. | #3
On 9/13/17 7:24 PM, Brown, Aaron F wrote:
>> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On Behalf
>> Of Christophe JAILLET
>> Sent: Monday, August 28, 2017 10:13 AM
>> To: Waskiewicz Jr, Peter <peter.waskiewicz.jr@intel.com>; Kirsher, Jeffrey T
>> <jeffrey.t.kirsher@intel.com>
>> Cc: netdev@vger.kernel.org; kernel-janitors@vger.kernel.org; intel-wired-
>> lan@lists.osuosl.org; linux-kernel@vger.kernel.org
>> Subject: Re: [Intel-wired-lan] [PATCH] igb: check memory allocation failure
>>
>> Le 28/08/2017 à 01:09, Waskiewicz Jr, Peter a écrit :
>>> On 8/27/17 2:42 AM, Christophe JAILLET wrote:
>>>> Check memory allocation failures and return -ENOMEM in such cases, as
>>>> already done for other memory allocations in this function.
>>>>
>>>> This avoids NULL pointers dereference.
>>>>
>>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>>>> ---
>>>>     drivers/net/ethernet/intel/igb/igb_main.c | 2 ++
>>>>     1 file changed, 2 insertions(+)
>>>>
> 
> This seems to be fine from a "it does not break in testing" perspective, so...
> 
> Tested-by: Aaron Brown <aaron.f.brown@intel.com
> 
>>> -PJ
>>>
>> Hi,
>>
>> in fact, there is no leak because the only caller of 'igb_sw_init()'
>> (i.e. 'igb_probe()'), already frees these resources in case of error,
>> see [1]
>>
>> These resources are also freed  in 'igb_remove()'.
>>
>> Best reagrds,
>> CJ
>>
>> [1]:
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-
>> next.git/tree/drivers/net/ethernet/intel/igb/igb_main.c#n2775
> 
> But is PJ's comment saying that it is not really necessary?  If so I tend to lean towards the don't touch it if it's not broken perspective.

I guess I didn't respond after Christophe replied, sorry about that. 
The patch is good to me.  It's definitely catching an issue where we're 
not checking for a memory failure, then just follows the same 
de-allocation path on unwind.

If you want it:

Acked-by: PJ Waskiewicz <peter.waskiewicz.jr@intel.com>

Patch

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index fd4a46b03cc8..837d9b46a390 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3162,6 +3162,8 @@  static int igb_sw_init(struct igb_adapter *adapter)
 	/* Setup and initialize a copy of the hw vlan table array */
 	adapter->shadow_vfta = kcalloc(E1000_VLAN_FILTER_TBL_SIZE, sizeof(u32),
 				       GFP_ATOMIC);
+	if (!adapter->shadow_vfta)
+		return -ENOMEM;
 
 	/* This call may decrease the number of queues */
 	if (igb_init_interrupt_scheme(adapter, true)) {