2022-11-08 02:10:00

by Ping-Ke Shih

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 <[email protected]>
Addresses-Coverity-ID: 1527095 ("Integer handling issues")
Fixes: e3ec7017f6a2 ("rtw89: add Realtek 802.11ax driver")
Signed-off-by: Ping-Ke Shih <[email protected]>
---
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

2022-11-09 07:06:37

by Kalle Valo

Subject: Re: [PATCH v2] wifi: rtw89: use u32_encode_bits() to fill MAC quota value

Ping-Ke Shih <[email protected]> wrote:

> 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 <[email protected]>
> Addresses-Coverity-ID: 1527095 ("Integer handling issues")
> Fixes: e3ec7017f6a2 ("rtw89: add Realtek 802.11ax driver")
> Signed-off-by: Ping-Ke Shih <[email protected]>

Patch applied to wireless-next.git, thanks.

525c06c81d75 wifi: rtw89: use u32_encode_bits() to fill MAC quota value

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

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