linux-kernel - Re: [PATCH] igb: check memory allocation failure

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Message-ID: <95a0bc80-8b41-d74f-8059-ae7181493120@wanadoo.fr>
Date:   Mon, 28 Aug 2017 19:12:30 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     linux-kernel@...r.kernel.org
Cc:     netdev@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [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@...adoo.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