Subject: Re: [net-next 15/16] igb: Fix Null-pointer dereference in igb_reset_q_vector

From: Christoph Paasch <[email-masked]>
Date: Sun, 23 Mar 2014 15:31:25 +0100

On 21/03/14 - 12:10:05, Jeff Kirsher wrote:
> From: Christoph Paasch <[email-masked]>
> 
> When igb_set_interrupt_capability() calls
> igb_reset_interrupt_capability() (e.g., because CONFIG_PCI_MSI is unset),
> num_q_vectors has been set but no vector has yet been allocated.
> 
> igb_reset_interrupt_capability() will then call igb_reset_q_vector,
> which assumes that the vector is allocated. As this is not the case, we
> are accessing a NULL-pointer.
> 
> This patch fixes it by checking that q_vector is indeed different from
> NULL.
> 
> Fixes: 02ef6e1d0b0023 (igb: Fix queue allocation method to accommodate changing during runtime)
> Cc: Carolyn Wyborny <[email-masked]>
> Signed-off-by: Christoph Paasch <[email-masked]>
> Tested-by: Jeff Pieper <[email-masked]>
> Signed-off-by: Jeff Kirsher <[email-masked]>

Hello Jeff,

shouldn't this one rather be for 'net' instead of 'net-next'? Because
02ef6e1d0b0023 is part of 3.14-rc1.

Cheers,
Christoph

> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index e8b4f7b..6acf787 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -1035,6 +1035,12 @@ static void igb_reset_q_vector(struct igb_adapter *adapter, int v_idx)
>  {
>  	struct igb_q_vector *q_vector = adapter->q_vector[v_idx];
>  
> +	/* Coming from igb_set_interrupt_capability, the vectors are not yet
> +	 * allocated. So, q_vector is NULL so we should stop here.
> +	 */
> +	if (!q_vector)
> +		return;
> +
>  	if (q_vector->tx.ring)
>  		adapter->tx_ring[q_vector->tx.ring->queue_index] = NULL;
>  
> -- 
> 1.8.3.1
>