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

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Message-Id: <20221009220754.1214186-3-sashal@kernel.org>
Date:   Sun,  9 Oct 2022 18:06:40 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zong-Zhe Yang <kevin_yang@...ltek.com>,
        Ping-Ke Shih <pkshih@...ltek.com>,
        Kalle Valo <kvalo@...nel.org>, Sasha Levin <sashal@...nel.org>,
        tony0620emma@...il.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.0 03/77] wifi: rtw88: phy: fix warning of possible buffer overflow

From: Zong-Zhe Yang <kevin_yang@...ltek.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@...ltek.com>
Signed-off-by: Ping-Ke Shih <pkshih@...ltek.com>
Signed-off-by: Kalle Valo <kvalo@...nel.org>
Link: https://lore.kernel.org/r/20220727065003.28340-5-pkshih@realtek.com
Signed-off-by: Sasha Levin <sashal@...nel.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