Re: [PATCH v2] net: wwan: iosm: drop redundant skb->data check in MUX DL decode

[Loic Poulain]

On Tue, Nov 3, 2026 at 3:59 PM Fang Xieyan <fangxy@xxxxxxxxxxxx> wrote:
>
> The skb passed to ipc_mux_dl_decode() through the current RX path
> always has a valid data pointer.
>
> The only caller, ipc_imem_dl_skb_process(), checks for a NULL skb
> before calling ipc_mux_dl_decode(). The skb is allocated through
> ipc_pcie_alloc_skb() -> ipc_pcie_alloc_local_skb() ->
> __netdev_alloc_skb(), which provides a valid data buffer on
> successful allocation. Allocation or DMA mapping failures return
> a NULL skb instead.
>
> Remove the redundant skb->data check.
>
> Suggested-by: Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>
> Reviewed-by: Guanglei Zhu <zhugl3@xxxxxxxxxxxx>
> Signed-off-by: Fang Xieyan <fangxy@xxxxxxxxxxxx>

On top of that, the early-return branch does not release the related resources.

Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>

> ---
> Changes in v2:
> - Drop the "fix potential skb leak" approach. The skb->data NULL
>   condition is unreachable through the current RX path, so remove
>   the redundant check instead of adding an ipc_pcie_kfree_skb() call.
> - Drop the Fixes: tag because this patch does not fix a reachable bug.
>
>  drivers/net/wwan/iosm/iosm_ipc_mux_codec.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c b/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c
> index 0bbd41263cc2..2b8a22980c87 100644
> --- a/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c
> +++ b/drivers/net/wwan/iosm/iosm_ipc_mux_codec.c
> @@ -693,9 +693,6 @@ void ipc_mux_dl_decode(struct iosm_mux *ipc_mux, struct sk_buff *skb)
>  {
>         u32 signature;
>
> -       if (!skb->data)
> -               return;
> -
>         /* Decode the MUX header type. */
>         signature = le32_to_cpup((__le32 *)skb->data);
>
> --
> 2.50.1
>