Re: [Intel-wired-lan] [PATCH iwl-net 1/2] ice: Fix deinitializing VF in error path

[Simon Horman <horms@kernel.org>]

On Tue, Feb 11, 2025 at 06:43:21PM +0100, Marcin Szycik wrote:
> If ice_ena_vfs() fails after calling ice_create_vf_entries(), it frees
> all VFs without removing them from snapshot PF-VF mailbox list, leading
> to list corruption.
> 
> Reproducer:
>   devlink dev eswitch set $PF1_PCI mode switchdev
>   ip l s $PF1 up
>   ip l s $PF1 promisc on
>   sleep 1
>   echo 1 > /sys/class/net/$PF1/device/sriov_numvfs

Should the line above be "echo 0" to remove the VFs before creating VFs
below (I'm looking at sriov_numvfs_store())?

>   sleep 1
>   echo 1 > /sys/class/net/$PF1/device/sriov_numvfs
> 
> Trace (minimized):
>   list_add corruption. next->prev should be prev (ffff8882e241c6f0), but was 0000000000000000. (next=ffff888455da1330).
>   kernel BUG at lib/list_debug.c:29!
>   RIP: 0010:__list_add_valid_or_report+0xa6/0x100
>    ice_mbx_init_vf_info+0xa7/0x180 [ice]
>    ice_initialize_vf_entry+0x1fa/0x250 [ice]
>    ice_sriov_configure+0x8d7/0x1520 [ice]
>    ? __percpu_ref_switch_mode+0x1b1/0x5d0
>    ? __pfx_ice_sriov_configure+0x10/0x10 [ice]
> 
> Sometimes a KASAN report can be seen instead with a similar stack trace:
>   BUG: KASAN: use-after-free in __list_add_valid_or_report+0xf1/0x100
> 
> VFs are added to this list in ice_mbx_init_vf_info(), but only removed
> in ice_free_vfs(). Move the removing to ice_free_vf_entries(), which is
> also being called in other places where VFs are being removed (including
> ice_free_vfs() itself).
> 
> Fixes: 8cd8a6b17d27 ("ice: move VF overflow message count into struct ice_mbx_vf_info")
> Reported-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
> Closes: https://lore.kernel.org/intel-wired-lan/PH0PR11MB50138B635F2E5CEB7075325D961F2@PH0PR11MB5013.namprd11.prod.outlook.com
> Reviewed-by: Martyna Szapar-Mudlaw <martyna.szapar-mudlaw@linux.intel.com>
> Signed-off-by: Marcin Szycik <marcin.szycik@linux.intel.com>

The comment above notwithstanding, I agree that this addresses the
bug you have described.

Reviewed-by: Simon Horman <horms@kernel.org>