[PATCH AUTOSEL 6.0 03/77] wifi: rtw88: phy: fix warning of possible buffer overflow

Sasha Levin
2022-10-09T22:08:16Z

From: Zong-Zhe Yang <kevin_yang@realtek.com>

[ Upstream commit 86331c7e0cd819bf0c1d0dcf895e0c90b0aa9a6f ]

reported by smatch

phy.c:854 rtw_phy_linear_2_db() error: buffer overflow 'db_invert_table[i]'
8 <= 8 (assuming for loop doesn't break)

However, it seems to be a false alarm because we prevent it originally via
if (linear >= db_invert_table[11][7])
return 96; /* maximum 96 dB */

Still, we adjust the code to be more readable and avoid smatch warning.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220727065003.28340-5-pkshih@realtek.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/realtek/rtw88/phy.c | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/phy.c b/drivers/net/wireless/realtek/rtw88/phy.c
index 8982e0c98dac..da1efec0aa85 100644
--- a/drivers/net/wireless/realtek/rtw88/phy.c
+++ b/drivers/net/wireless/realtek/rtw88/phy.c
@@ -816,23 +816,18 @@ static u8 rtw_phy_linear_2_db(u64 linear)
u8 j;
u32 dB;

- if (linear >= db_invert_table[11][7])
- return 96; /* maximum 96 dB */
-
for (i = 0; i < 12; i++) {
- if (i <= 2 && (linear << FRAC_BITS) <= db_invert_table[i][7])
- break;
- else if (i > 2 && linear <= db_invert_table[i][7])
- break;
+ for (j = 0; j < 8; j++) {
+ if (i <= 2 && (linear << FRAC_BITS) <= db_invert_table[i][j])
+ goto cnt;
+ else if (i > 2 && linear <= db_invert_table[i][j])
+ goto cnt;
+ }
}

- for (j = 0; j < 8; j++) {
- if (i <= 2 && (linear << FRAC_BITS) <= db_invert_table[i][j])
- break;
- else if (i > 2 && linear <= db_invert_table[i][j])
- break;
- }
+ return 96; /* maximum 96 dB */

+cnt:
if (j == 0 && i == 0)
goto end;

--
2.35.1