netdev - Re: [PATCH] igb: Fix null pointer dereference

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Date:	Wed, 13 Mar 2013 00:51:18 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	gregory.v.rose@...el.com, netdev@...r.kernel.org,
	ddutile@...hat.com, linux-kernel@...r.kernel.org,
	sassmann@...hat.com
Subject: Re: [PATCH] igb: Fix null pointer dereference

On Tue, 2013-03-12 at 14:09 -0600, Alex Williamson wrote:
> The max_vfs= option has always been self limiting to the number of VFs
> supported by the device.  fa44f2f1 added SR-IOV configuration via
> sysfs, but in the process broke this self correction factor.  The
> failing path is:
> 
> igb_probe
>   igb_sw_init
>     if (max_vfs > 7) {
>         adapter->vfs_allocated_count = 7;
>     ...
>     igb_probe_vfs
>     igb_enable_sriov(, max_vfs)
>       if (num_vfs > 7) {
>         err = -EPERM;
>         ...
> 
> This leaves vfs_allocated_count = 7 and vf_data = NULL, so we bomb out
> when igb_probe finally calls igb_reset.  It seems like a really bad
> idea, and somewhat pointless, to set vfs_allocated_count separate from
> vf_data, but limiting max_vfs is enough to avoid the null pointer.
> 
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-) 

I have added the patch to my igb queue, thanks!

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