diff mbox series

wifi: iwlwifi: mvm: Fix __counted_by usage in cfg80211_wowlan_nd_*

Message ID 20240619211233.work.355-kees@kernel.org
State New
Headers show
Series wifi: iwlwifi: mvm: Fix __counted_by usage in cfg80211_wowlan_nd_* | expand

Commit Message

Kees Cook June 19, 2024, 9:12 p.m. UTC 
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")
Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Cc: Yedidya Benshimol <yedidya.ben.shimol@intel.com>
Cc: Haim Dreyfuss <haim.dreyfuss@intel.com>
Cc: linux-wireless@vger.kernel.org
---
 drivers/net/wireless/intel/iwlwifi/mvm/d3.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

Comments

Christophe JAILLET June 20, 2024, 6:53 p.m. UTC | #1 
Le 20/06/2024 à 20:08, Gustavo A. R. Silva a écrit :
> 
> 
> On 6/20/24 12:02, Gustavo A. R. Silva wrote:
>>
>>> My understanding is that 'match', is allocated by :
>>>      match = kzalloc(struct_size(match, channels, n_channels), 
>>> GFP_KERNEL);
>>>
>>> So match->n_channels is *0* when iwl_mvm_query_set_freqs() is called.
>>
>> n_channels is updated in the line before calling kzalloc():
>>
>> n_channels = iwl_mvm_query_num_match_chans(mvm, d3_data->nd_results, i);
>>
>> match = kzalloc(struct_size(match, channels, n_channels), GFP_KERNEL);
> 
> then match->n_channels updated here:
> 
>           if (!match)
>               goto out_report_nd;
> +        match->n_channels = n_channels;

Thanks for the explanation.
This is what I was looking for, and I missed this line.

Sorry for the noise.

CJ

> 
> Sorry about the split response, finger failure ugghh
> 
> -- 
> Gustavo
> 
>
diff mbox series

Patch

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/d3.c b/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
index 54f4acbbd05b..9cd03ea4680d 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/d3.c
@@ -2866,6 +2866,7 @@  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)) {
@@ -2874,7 +2875,7 @@  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 =
@@ -2882,9 +2883,11 @@  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;
 }
 
 /**
@@ -2965,6 +2968,8 @@  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;
@@ -2978,8 +2983,9 @@  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.
@@ -2994,6 +3000,8 @@  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;