[Intel-wired-lan] [PATCH] i40e: check __I40E_VF_DISABLE bit in i40e_sync_filters_subtask

[Bowers, AndrewX <andrewx.bowers@intel.com>]

> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On
> Behalf Of Stefan Assmann
> Sent: Wednesday, August 21, 2019 7:09 AM
> To: intel-wired-lan at lists.osuosl.org
> Cc: netdev at vger.kernel.org; davem at davemloft.net; sassmann at kpanic.de
> Subject: [Intel-wired-lan] [PATCH] i40e: check __I40E_VF_DISABLE bit in
> i40e_sync_filters_subtask
> 
> While testing VF spawn/destroy the following panic occured.
> 
> BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000029 [...]
> Workqueue: i40e i40e_service_task [i40e]
> RIP: 0010:i40e_sync_vsi_filters+0x6fd/0xc60 [i40e] [...] Call Trace:
>  ? __switch_to_asm+0x35/0x70
>  ? __switch_to_asm+0x41/0x70
>  ? __switch_to_asm+0x35/0x70
>  ? _cond_resched+0x15/0x30
>  i40e_sync_filters_subtask+0x56/0x70 [i40e]
>  i40e_service_task+0x382/0x11b0 [i40e]
>  ? __switch_to_asm+0x41/0x70
>  ? __switch_to_asm+0x41/0x70
>  process_one_work+0x1a7/0x3b0
>  worker_thread+0x30/0x390
>  ? create_worker+0x1a0/0x1a0
>  kthread+0x112/0x130
>  ? kthread_bind+0x30/0x30
>  ret_from_fork+0x35/0x40
> 
> Investigation revealed a race where pf->vf[vsi->vf_id].trusted may get
> accessed by the watchdog via i40e_sync_filters_subtask() although
> i40e_free_vfs() already free'd pf->vf.
> To avoid this the call to i40e_sync_vsi_filters() in
> i40e_sync_filters_subtask() needs to be guarded by __I40E_VF_DISABLE,
> which is also used by i40e_free_vfs().
> 
> Note: put the __I40E_VF_DISABLE check after the
> __I40E_MACVLAN_SYNC_PENDING check as the latter is more likely to
> trigger.
> 
> Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 5 +++++
>  1 file changed, 5 insertions(+)

Tested-by: Andrew Bowers <andrewx.bowers@intel.com>