RE: [Intel-wired-lan] [PATCH iwl-net v2] idpf: fix corrupted frames and skb leaks in singleq mode

[Register, Scott]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of
> Alexander Lobakin
> Sent: Monday, December 11, 2023 4:32 AM
> To: intel-wired-lan@xxxxxxxxxxxxxxxx
> Cc: Fijalkowski, Maciej <maciej.fijalkowski@xxxxxxxxx>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; Lobakin,
> Aleksander <aleksander.lobakin@xxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Kubiak, Michal <michal.kubiak@xxxxxxxxx>;
> Simon Horman <horms@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; Jakub
> Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; David S.
> Miller <davem@xxxxxxxxxxxxx>
> Subject: [Intel-wired-lan] [PATCH iwl-net v2] idpf: fix corrupted frames and
> skb leaks in singleq mode
> 
> idpf_ring::skb serves only for keeping an incomplete frame between
> several NAPI Rx polling cycles, as one cycle may end up before
> processing the end of packet descriptor. The pointer is taken from
> the ring onto the stack before entering the loop and gets written
> there after the loop exits. When inside the loop, only the onstack
> pointer is used.
> For some reason, the logics is broken in the singleq mode, where the
> pointer is taken from the ring each iteration. This means that if a
> frame got fragmented into several descriptors, each fragment will have
> its own skb, but only the last one will be passed up the stack
> (containing garbage), leaving the rest leaked.
> Then, on ifdown, rxq::skb is being freed only in the splitq mode, while
> it can point to a valid skb in singleq as well. This can lead to a yet
> another skb leak.
> Just don't touch the ring skb field inside the polling loop, letting
> the onstack skb pointer work as expected: build a new skb if it's the
> first frame descriptor and attach a frag otherwise. On ifdown, free
> rxq::skb unconditionally if the pointer is non-NULL.
> 
> Fixes: a5ab9ee0df0b ("idpf: add singleq start_xmit and napi poll")
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@xxxxxxxxx>
> Reviewed-by: Michal Kubiak <michal.kubiak@xxxxxxxxx>
> Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
> ---
> Tony, please add it to dev-queue instead of the first revision.
> 
> From v1[0]:
> * fix the related skb leak on ifdown;
> * fix subject prefix;
> * pick Reviewed-bys.
> 
> [0] https://lore.kernel.org/all/20231201143821.1091005-1-
> aleksander.lobakin@xxxxxxxxx
> ---
>  drivers/net/ethernet/intel/idpf/idpf_singleq_txrx.c | 1 -
>  drivers/net/ethernet/intel/idpf/idpf_txrx.c         | 2 +-
>  2 files changed, 1 insertion(+), 2 deletions(-)

Tested-by: Scott Register <scott.register@xxxxxxxxx>