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Subject[PATCH v2] ethtool: avoiding integer overflow in ethtool_phys_id()
Date
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>
---
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 6a7308de192d..f845e8be4d7c 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -2007,7 +2007,8 @@ 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();
--
2.17.1
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