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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zong-Zhe Yang <kevin_yang@realtek.com>,
        Ping-Ke Shih <pkshih@realtek.com>,
        Kalle Valo <kvalo@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.0 681/862] wifi: rtw88: phy: fix warning of possible buffer overflow
Date:   Wed, 19 Oct 2022 10:32:48 +0200
Message-Id: <20221019083320.063888989@linuxfoundation.org>
In-Reply-To: <20221019083249.951566199@linuxfoundation.org>
References: <20221019083249.951566199@linuxfoundation.org>
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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