> -----Original Message-----
> From: Kees Cook <[email protected]>
> Sent: Monday, 16 December 2024 6:29
> To: Christophe JAILLET <[email protected]>
> Cc: Kees Cook <[email protected]>; Gustavo A . R . Silva 
> <[email protected]>;
> Korenblit, Miriam Rachel <[email protected]>; Kalle Valo
> <[email protected]>; Berg, Johannes <[email protected]>; Triebitz, Shaul
> <[email protected]>; Grumbach, Emmanuel
> <[email protected]>; Ben Shimol, Yedidya
> <[email protected]>; Berg, Benjamin <[email protected]>;
> Dmitry Antipov <[email protected]>; [email protected]; linux-
> [email protected]; [email protected]
> Subject: [PATCH RESEND] wifi: iwlwifi: mvm: Fix __counted_by usage in
> cfg80211_wowlan_nd_*
> 
> Both struct cfg80211_wowlan_nd_match and struct cfg80211_wowlan_nd_info
> pre-allocate space for channels and matches, but then may end up using fewer
> that the full allocation. Shrink the associated counter (n_channels and 
> n_matches)
> after counting the results. This avoids compile-time (and run-time) warnings 
> from
> __counted_by. (The counter member needs to be updated _before_ accessing the
> array index.)
> 
> Seen with coming GCC 15:
> 
> drivers/net/wireless/intel/iwlwifi/mvm/d3.c: In function
> 'iwl_mvm_query_set_freqs':
> drivers/net/wireless/intel/iwlwifi/mvm/d3.c:2877:66: warning: operation on
> 'match->n_channels' may be undefined [-Wsequence-point]
>  2877 |                                 match->channels[match->n_channels++] =
>       |                                                 ~~~~~~~~~~~~~~~~~^~
> drivers/net/wireless/intel/iwlwifi/mvm/d3.c:2885:66: warning: operation on
> 'match->n_channels' may be undefined [-Wsequence-point]
>  2885 |                                 match->channels[match->n_channels++] =
>       |                                                 ~~~~~~~~~~~~~~~~~^~
> drivers/net/wireless/intel/iwlwifi/mvm/d3.c: In function
> 'iwl_mvm_query_netdetect_reasons':
> drivers/net/wireless/intel/iwlwifi/mvm/d3.c:2982:58: warning: operation on
> 'net_detect->n_matches' may be undefined [-Wsequence-point]
>  2982 |                 net_detect->matches[net_detect->n_matches++] = match;
>       |                                     ~~~~~~~~~~~~~~~~~~~~~^~
> 
> Fixes: aa4ec06c455d ("wifi: cfg80211: use __counted_by where appropriate")
> Reviewed-by: Gustavo A. R. Silva <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> Pinging this patch again, see
> https://lore.kernel.org/lkml/[email protected]/
> ---
>  drivers/net/wireless/intel/iwlwifi/mvm/d3.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
> b/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
> index f85c01e04ebf..7d973546c9fb 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
> @@ -2954,6 +2954,7 @@ static void iwl_mvm_query_set_freqs(struct iwl_mvm
> *mvm,
>                                   int idx)
>  {
>       int i;
> +     int n_channels = 0;
> 
>       if (fw_has_api(&mvm->fw->ucode_capa,
>                      IWL_UCODE_TLV_API_SCAN_OFFLOAD_CHANS)) { @@ -
> 2962,7 +2963,7 @@ static void iwl_mvm_query_set_freqs(struct iwl_mvm
> *mvm,
> 
>               for (i = 0; i < SCAN_OFFLOAD_MATCHING_CHANNELS_LEN * 8;
> i++)
>                       if (matches[idx].matching_channels[i / 8] & (BIT(i % 
> 8)))
> -                             match->channels[match->n_channels++] =
> +                             match->channels[n_channels++] =
>                                       mvm->nd_channels[i]->center_freq;
>       } else {
>               struct iwl_scan_offload_profile_match_v1 *matches = @@ -
> 2970,9 +2971,11 @@ static void iwl_mvm_query_set_freqs(struct iwl_mvm
> *mvm,
> 
>               for (i = 0; i < SCAN_OFFLOAD_MATCHING_CHANNELS_LEN_V1 *
> 8; i++)
>                       if (matches[idx].matching_channels[i / 8] & (BIT(i % 
> 8)))
> -                             match->channels[match->n_channels++] =
> +                             match->channels[n_channels++] =
>                                       mvm->nd_channels[i]->center_freq;
>       }
> +     /* We may have ended up with fewer channels than we allocated. */
> +     match->n_channels = n_channels;
>  }
> 
>  /**
> @@ -3053,6 +3056,8 @@ static void iwl_mvm_query_netdetect_reasons(struct
> iwl_mvm *mvm,
>                            GFP_KERNEL);
>       if (!net_detect || !n_matches)
>               goto out_report_nd;
> +     net_detect->n_matches = n_matches;
> +     n_matches = 0;
> 
>       for_each_set_bit(i, &matched_profiles, mvm->n_nd_match_sets) {
>               struct cfg80211_wowlan_nd_match *match; @@ -3066,8
> +3071,9 @@ static void iwl_mvm_query_netdetect_reasons(struct iwl_mvm
> *mvm,
>                               GFP_KERNEL);
>               if (!match)
>                       goto out_report_nd;
> +             match->n_channels = n_channels;
> 
> -             net_detect->matches[net_detect->n_matches++] = match;
> +             net_detect->matches[n_matches++] = match;
> 
>               /* We inverted the order of the SSIDs in the scan
>                * request, so invert the index here.
> @@ -3082,6 +3088,8 @@ static void iwl_mvm_query_netdetect_reasons(struct
> iwl_mvm *mvm,
> 
>               iwl_mvm_query_set_freqs(mvm, d3_data->nd_results, match, i);
>       }
> +     /* We may have fewer matches than we allocated. */
> +     net_detect->n_matches = n_matches;
> 
>  out_report_nd:
>       wakeup.net_detect = net_detect;
> --
> 2.34.1

Hi ,

The patch was already applied and marked in Patchwork as such. 

Miri

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