Subject: Re: [PATCH iwl-net v1] i40e: Fix macvlan leak by synchronizing access to mac_filter_hash

From: Simon Horman <[email-masked]>
Date: Tue, 24 Sep 2024 07:56:48 +0100

On Mon, Sep 23, 2024 at 11:12:19AM +0200, Aleksandr Loktionov wrote:
> This patch addresses a macvlan leak issue in the i40e driver caused by
> concurrent access to vsi->mac_filter_hash. The leak occurs when multiple
> threads attempt to modify the mac_filter_hash simultaneously, leading to
> inconsistent state and potential memory leaks.
> 
> To fix this, we now wrap the calls to i40e_del_mac_filter() and zeroing
> vf->default_lan_addr.addr with spin_lock/unlock_bh(&vsi->mac_filter_hash_lock),
> ensuring atomic operations and preventing concurrent access.
> 
> Additionally, we add lockdep_assert_held(&vsi->mac_filter_hash_lock) in
> i40e_add_mac_filter() to help catch similar issues in the future.
> 
> Reproduction steps:
> 1. Spawn VFs and configure port vlan on them.
> 2. Trigger concurrent macvlan operations (e.g., adding and deleting
> 	portvlan and/or mac filters).
> 3. Observe the potential memory leak and inconsistent state in the
> 	mac_filter_hash.
> 
> This synchronization ensures the integrity of the mac_filter_hash and prevents
> the described leak.
> 
> Fixes: fed0d9f13266 ("i40e: Fix VF's MAC Address change on VM")
> Reviewed-by: Arkadiusz Kubalewski <[email-masked]>
> Signed-off-by: Aleksandr Loktionov <[email-masked]>

Thanks Aleksandr,

I see that:

1) All calls to i40e_add_mac_filter() and all other calls
   to i40e_del_mac_filter() are already protected by
   vsi->mac_filter_hash_lock.

2) i40e_del_mac_filter() already asserts that
   vsi->mac_filter_hash_lock is held.

So this looks good to me.

Reviewed-by: Simon Horman <[email-masked]>

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