ath10k: abstract htt_rx_desc structure

Hello Francesco Magliocca,

The patch 6bae9de622d3: "ath10k: abstract htt_rx_desc structure" from Jan 12, 2022, leads to the following Smatch static checker warning:

	drivers/net/wireless/ath/ath10k/htt_rx.c:432 ath10k_htt_rx_amsdu_pop()
	warn: potential pointer math issue ('rx_desc' is a 32 bit pointer)

drivers/net/wireless/ath/ath10k/htt_rx.c

    346 static int ath10k_htt_rx_amsdu_pop(struct ath10k_htt *htt,
    347                                    struct sk_buff_head *amsdu)
    348 {
    349         struct ath10k *ar = htt->ar;
    350         struct ath10k_hw_params *hw = &ar->hw_params;
    351         int msdu_len, msdu_chaining = 0;
    352         struct sk_buff *msdu;
    353         struct htt_rx_desc *rx_desc;
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    354         struct rx_attention *rx_desc_attention;
    355         struct rx_frag_info_common *rx_desc_frag_info_common;
    356         struct rx_msdu_start_common *rx_desc_msdu_start_common;
    357         struct rx_msdu_end_common *rx_desc_msdu_end_common;
    358 

[ snip ]

    427 
    428                 last_msdu = __le32_to_cpu(rx_desc_msdu_end_common->info0) &
    429                                 RX_MSDU_END_INFO0_LAST_MSDU;
    430 
    431                 /* FIXME: why are we skipping the first part of the rx_desc? */
--> 432                 trace_ath10k_htt_rx_desc(ar, rx_desc + sizeof(u32),
                                                     ^^^^^^^^^^^^^^^^^^^^^

This is a pointer math bug. It's possible that it should be:

	trace_ath10k_htt_rx_desc(ar, (u8 *)rx_desc + sizeof(u32),

But as your FIXME notes, it's hard to tell what's going on here...

    433                                          hw->rx_desc_ops->rx_desc_size - sizeof(u32));
    434 
    435                 if (last_msdu)
    436                         break;
    437         }

regards,
dan carpenter

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Hello Dan Carpenter,
auch, nice catch, thank you very much.
Yes, your solution is correct,
even if I think that we could avoid skipping the first part of the rx_desc altogether,
because it is just a trace.

Kalle, will you amend my commit or do I need to file a new patch?

Best regards,
Francesco Magliocca

Il giorno mar 1 feb 2022 alle ore 14:09 Dan Carpenter <[email protected]> ha scritto:

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I don't rebase my trees, so please submit a new patch fixing this issue.

https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

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