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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Maxim Korotkov <korotkov.maxim.s@gmail.com>,
        Alexander Lobakin <alexandr.lobakin@intel.com>,
        Andrew Lunn <andrew@lunn.ch>, Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>, davem@davemloft.net,
        edumazet@google.com, pabeni@redhat.com, f.fainelli@gmail.com,
        trix@redhat.com, wsa+renesas@sang-engineering.com,
        sean.anderson@seco.com, marco@mebeim.net, netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 5.15 33/46] ethtool: avoiding integer overflow in ethtool_phys_id()
Date:   Sun, 18 Dec 2022 11:12:31 -0500
Message-Id: <20221218161244.930785-33-sashal@kernel.org>
In-Reply-To: <20221218161244.930785-1-sashal@kernel.org>
References: <20221218161244.930785-1-sashal@kernel.org>
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From: Maxim Korotkov <korotkov.maxim.s@gmail.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@gmail.com>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20221122122901.22294-1-korotkov.maxim.s@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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