[PATCH] staging: rtl8723bs: avoid duplicate size computation in rtw_spt_band_alloc

[PATCH] staging: rtl8723bs: avoid duplicate size computation in rtw_spt_band_alloc

[Serhat Kumral]

Introduce a local variable to store the channel array size and reuse it
for both the allocation and the bitrates pointer offset, replacing a
redundant open-coded multiplication with the same array_size() result.

Resolves the Coccinelle warning:
WARNING: array_size is already used (line 124) to compute the same size

Signed-off-by: Serhat Kumral <serhatkumral1@gmail.com>
---
 drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
index 1484336d7..2e65788ee 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
@@ -111,7 +111,7 @@ static struct ieee80211_supported_band *rtw_spt_band_alloc(
 {
 	struct ieee80211_supported_band *spt_band = NULL;
 	int n_channels, n_bitrates;
-	size_t alloc_sz;
+	size_t alloc_sz, channels_sz;
 
 	if (band == NL80211_BAND_2GHZ) {
 		n_channels = RTW_2G_CHANNELS_NUM;
@@ -120,15 +120,16 @@ static struct ieee80211_supported_band *rtw_spt_band_alloc(
 		goto exit;
 	}
 
+	channels_sz = array_size(n_channels, sizeof(struct ieee80211_channel));
 	alloc_sz = sizeof(*spt_band);
-	alloc_sz = size_add(alloc_sz, array_size(n_channels, sizeof(struct ieee80211_channel)));
+	alloc_sz = size_add(alloc_sz, channels_sz);
 	alloc_sz = size_add(alloc_sz, array_size(n_bitrates, sizeof(struct ieee80211_rate)));
 	spt_band = kzalloc(alloc_sz, GFP_KERNEL);
 	if (!spt_band)
 		goto exit;
 
 	spt_band->channels = (struct ieee80211_channel *)(((u8 *)spt_band) + sizeof(struct ieee80211_supported_band));
-	spt_band->bitrates = (struct ieee80211_rate *)(((u8 *)spt_band->channels) + sizeof(struct ieee80211_channel) * n_channels);
+	spt_band->bitrates = (struct ieee80211_rate *)(((u8 *)spt_band->channels) + channels_sz);
 	spt_band->band = band;
 	spt_band->n_channels = n_channels;
 	spt_band->n_bitrates = n_bitrates;
-- 
2.54.0

Re: [PATCH] staging: rtl8723bs: avoid duplicate size computation in rtw_spt_band_alloc

[Dan Carpenter]

On Sun, Jun 21, 2026 at 04:33:01PM +0300, Serhat Kumral wrote:
> Introduce a local variable to store the channel array size and reuse it
> for both the allocation and the bitrates pointer offset, replacing a
> redundant open-coded multiplication with the same array_size() result.
> 
> Resolves the Coccinelle warning:
> WARNING: array_size is already used (line 124) to compute the same size
> 
> Signed-off-by: Serhat Kumral <serhatkumral1@gmail.com>
> ---
>  drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> index 1484336d7..2e65788ee 100644
> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> @@ -111,7 +111,7 @@ static struct ieee80211_supported_band *rtw_spt_band_alloc(
>  {
>  	struct ieee80211_supported_band *spt_band = NULL;
>  	int n_channels, n_bitrates;
> -	size_t alloc_sz;
> +	size_t alloc_sz, channels_sz;
>  
>  	if (band == NL80211_BAND_2GHZ) {
>  		n_channels = RTW_2G_CHANNELS_NUM;
> @@ -120,15 +120,16 @@ static struct ieee80211_supported_band *rtw_spt_band_alloc(
>  		goto exit;
>  	}
>  
> +	channels_sz = array_size(n_channels, sizeof(struct ieee80211_channel));
>  	alloc_sz = sizeof(*spt_band);
> -	alloc_sz = size_add(alloc_sz, array_size(n_channels, sizeof(struct ieee80211_channel)));
> +	alloc_sz = size_add(alloc_sz, channels_sz);
>  	alloc_sz = size_add(alloc_sz, array_size(n_bitrates, sizeof(struct ieee80211_rate)));
>  	spt_band = kzalloc(alloc_sz, GFP_KERNEL);

This is still a mess.  First of all these size values are constant so
the layers of indirection are unnecessary.  Pretending they are variable
makes code auditors have to check for integer overflows so it wastes
valuable time and makes the whole kernel less secure.

	channels_sz = array_size(RTW_2G_CHANNELS_NUM, sizeof(struct ieee80211_channel));
	bitrate_size = array_size(RTW_G_RATES_NUM, sizeof(struct ieee80211_rate));

	spt_band = kzalloc(sizeof(*spt_band) + channels_sz + bitrate_size, GFP_KERNEL);

	spt_band->channels = (void *)spt_band + sizeof(*spt_band);
	spt_band->bitrates = (void *)spt_band + sizeof(*spt_band) + channels_sz;

regards,
dan carpenter