2017-08-27 06:41:55

by Christophe JAILLET

Subject: [PATCH] igb: check memory allocation failure

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 <[email protected]>
---
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;

/* This call may decrease the number of queues */
if (igb_init_interrupt_scheme(adapter, true)) {
--
2.11.0

2017-08-27 23:09:17

by Waskiewicz Jr, Peter

Subject: Re: [PATCH] igb: check memory allocation failure

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 <[email protected]>
> ---
> 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

2017-08-28 17:12:43

by Christophe JAILLET

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 <[email protected]>
>> ---
>> 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

2017-09-14 02:24:41

by Brown, Aaron F

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

> From: Intel-wired-lan [mailto:[email protected]] On Behalf
> Of Christophe JAILLET
> Sent: Monday, August 28, 2017 10:13 AM
> To: Waskiewicz Jr, Peter <[email protected]>; Kirsher, Jeffrey T
> <[email protected]>
> Cc: [email protected]; [email protected]; intel-wired-
> [email protected]; [email protected]
> 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 <[email protected]>
> >> ---
> >> 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 <[email protected]

> > -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.