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From:   Ping-Ke Shih <pkshih@realtek.com>
To:     Ping-Ke Shih <pkshih@realtek.com>,
        "kvalo@kernel.org" <kvalo@kernel.org>
CC:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: RE: [PATCH v2] wifi: rtw89: use u32_encode_bits() to fill MAC quota value
Thread-Topic: [PATCH v2] wifi: rtw89: use u32_encode_bits() to fill MAC quota
 value
Thread-Index: AQHY8xL7uwkfCE/Zqk6qrRDHJiaYwK40QmvA
Date:   Tue, 8 Nov 2022 01:50:26 +0000
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References: <20221108013858.10806-1-pkshih@realtek.com>
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> -----Original Message-----
> From: Ping-Ke Shih <pkshih@realtek.com>
> Sent: Tuesday, November 8, 2022 9:39 AM
> To: kvalo@kernel.org
> Cc: linux-wireless@vger.kernel.org
> Subject: [PATCH v2] wifi: rtw89: use u32_encode_bits() to fill MAC quota value
> 
> Coverity reported shift 16 bits could cause sign extension and might get
> an unexpected value. Since the input values are predefined and no this
> kind of case, original code is safe so far. But, still changing them to
> use u32_encode_bits() will be more clear and prevent mistakes in the
> future.
> 
> The original message of Coverity is:
>   Suspicious implicit sign extension: "max_cfg->cma0_dma" with type "u16"
>   (16 bits, unsigned) is promoted in "max_cfg->cma0_dma << 16" to type
>   "int" (32 bits, signed), then sign-extended to type "unsigned long"
>   (64 bits, unsigned).  If "max_cfg->cma0_dma << 16" is greater than
>   0x7FFFFFFF, the upper bits of the result will all be 1."
> 
> Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
> Addresses-Coverity-ID: 1527095 ("Integer handling issues")
> Fixes: e3ec7017f6a2 ("rtw89: add Realtek 802.11ax driver")
> Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>

Sorry, I forget to add changelog of v2.

v2: use u32_encode_bits() instead of FIELD_PREP() to set field value.

> ---
>  drivers/net/wireless/realtek/rtw89/mac.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtw89/mac.c b/drivers/net/wireless/realtek/rtw89/mac.c
> index bb49033b587d2..814ca4bc22587 100644
> --- a/drivers/net/wireless/realtek/rtw89/mac.c
> +++ b/drivers/net/wireless/realtek/rtw89/mac.c
> @@ -1487,10 +1487,8 @@ static int dle_mix_cfg(struct rtw89_dev *rtwdev, const struct rtw89_dle_mem *cfg
>  #define INVALID_QT_WCPU U16_MAX
>  #define SET_QUOTA_VAL(_min_x, _max_x, _module, _idx)			\
>  	do {								\
> -		val = ((_min_x) &					\
> -		       B_AX_ ## _module ## _MIN_SIZE_MASK) |		\
> -		      (((_max_x) << 16) &				\
> -		       B_AX_ ## _module ## _MAX_SIZE_MASK);		\
> +		val = u32_encode_bits(_min_x, B_AX_ ## _module ## _MIN_SIZE_MASK) | \
> +		      u32_encode_bits(_max_x, B_AX_ ## _module ## _MAX_SIZE_MASK);  \
>  		rtw89_write32(rtwdev,					\
>  			      R_AX_ ## _module ## _QTA ## _idx ## _CFG,	\
>  			      val);					\
> --
> 2.25.1
> 
> 
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