netdev - [PATCH AUTOSEL 5.15 33/46] ethtool: avoiding integer overflow in ethtool_phys

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Message-Id: <20221218161244.930785-33-sashal@kernel.org>
Date:   Sun, 18 Dec 2022 11:12:31 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Maxim Korotkov <korotkov.maxim.s@...il.com>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>, davem@...emloft.net,
        edumazet@...gle.com, pabeni@...hat.com, f.fainelli@...il.com,
        trix@...hat.com, wsa+renesas@...g-engineering.com,
        sean.anderson@...o.com, marco@...eim.net, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 33/46] ethtool: avoiding integer overflow in ethtool_phys_id()

From: Maxim Korotkov <korotkov.maxim.s@...il.com>

[ Upstream commit 64a8f8f7127da228d59a39e2c5e75f86590f90b4 ]

The value of an arithmetic expression "n * id.data" is subject
to possible overflow due to a failure to cast operands to a larger data
type before performing arithmetic. Used macro for multiplication instead
operator for avoiding overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Maxim Korotkov <korotkov.maxim.s@...il.com>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@...el.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Link: https://lore.kernel.org/r/20221122122901.22294-1-korotkov.maxim.s@gmail.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/ethtool/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index e4983f473a3c..6991d77dcb2e 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1988,7 +1988,8 @@ static int ethtool_phys_id(struct net_device *dev, void __user *useraddr)
 	} else {
 		/* Driver expects to be called at twice the frequency in rc */
 		int n = rc * 2, interval = HZ / n;
-		u64 count = n * id.data, i = 0;
+		u64 count = mul_u32_u32(n, id.data);
+		u64 i = 0;
 
 		do {
 			rtnl_lock();
-- 
2.35.1