Subject: Re: [PATCH v3 net] ixgbe: check adapter->vfinfo before dereference

From: Thierry Herbelot <[email-masked]>
Date: Thu, 16 Oct 2014 09:23:01 +0200

On 10/16/2014 12:50 AM, Tantilov, Emil S wrote:
>> -----Original Message-----
>> From: Thierry Herbelot [mailto:[email-masked]]
>> Sent: Wednesday, October 15, 2014 2:58 AM
>> To: Kirsher, Jeffrey T; Brandeburg, Jesse; Allan, Bruce W;
>> [email-masked]; Tantilov, Emil S
>> Cc: Thierry Herbelot
>> Subject: [PATCH v3 net] ixgbe: check adapter->vfinfo before dereference
>>
>> this protects against the following panic:
>> (before a VF was actually created on p96p1 PF Ethernet port)
>>
>> ip link set p96p1 vf 0 spoofchk off
>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000052
>> IP: [<ffffffffa044a1c1>]
>> ixgbe_ndo_set_vf_spoofchk+0x51/0x150 [ixgbe]
>>
>> Signed-off-by: Thierry Herbelot <[email-masked]>
>> ---
>>
>> v2:
>>   compilation fixes
>>
>> v3:
>>   remove checks in functions where vfinfo is known not to be NULL
>>   return -EINVAL as error code
>>
>> drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c |   42
>> ++++++++++++++++++++++--
>> 1 file changed, 40 insertions(+), 2 deletions(-)
>
> Actually looking into this a bit more, the check for vfinfo is not sufficient
> because it does not protect against specifying vf that is outside of sriov_num_vfs range.
>
> All of the ndo functions have a check for it except for ixgbevf_ndo_set_spoofcheck().
>
> The following patch should be all we need to protect against this panic:
>
> This patch adds a check to return -EINVAL when setting spoofcheck on
> VF that is not configured.
>
> Reported-by: Thierry Herbelot <[email-masked]>
> Signed-off-by: Emil Tantilov <[email-masked]>
> ---
>   drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c |    3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> index 706fc69..97c85b8 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> @@ -1261,6 +1261,9 @@ int ixgbe_ndo_set_vf_spoofchk(struct net_device *netdev, int vf, bool setting)
>   	struct ixgbe_hw *hw = &adapter->hw;
>   	u32 regval;
>
> +	if (vf >= adapter->num_vfs)
> +		return -EINVAL;
> +
>   	adapter->vfinfo[vf].spoofchk_enabled = setting;
>
>   	regval = IXGBE_READ_REG(hw, IXGBE_PFVFSPOOF(vf_target_reg));
>
>

Hello,

Indeed your patch solves the initial issue.

And indeed I also double-checked that all other instances are protected 
by the (vf >= adapter->num_vfs) condition.

	Best regards

	Thierry

-- 
Thierry Herbelot
6WIND
Software Engineer