netdev - [PATCH] net: ethtool: Return -EOPNOTSUPP if user space tries to read EEPROM with lengh 0

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Message-Id: <1414727415-5470-1-git-send-email-linux@roeck-us.net>
Date:	Thu, 30 Oct 2014 20:50:15 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Andrew Lunn <andrew@...n.ch>, linux-kernel@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] net: ethtool: Return -EOPNOTSUPP if user space tries to read EEPROM with lengh 0

If a driver supports reading EEPROM but no EEPROM is installed in the system,
the driver's get_eeprom_len function returns 0. ethtool will subsequently
try to read that zero-length EEPROM anyway. If the driver does not support
EEPROM access at all, this operation will return -EOPNOTSUPP. If the driver
does support EEPROM access but no EEPROM is installed, the operation will
return -EINVAL. Return -EOPNOTSUPP in both cases for consistency.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 net/core/ethtool.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 1600aa2..06dfb29 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1036,7 +1036,8 @@ static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
 {
 	const struct ethtool_ops *ops = dev->ethtool_ops;
 
-	if (!ops->get_eeprom || !ops->get_eeprom_len)
+	if (!ops->get_eeprom || !ops->get_eeprom_len ||
+	    !ops->get_eeprom_len(dev))
 		return -EOPNOTSUPP;
 
 	return ethtool_get_any_eeprom(dev, useraddr, ops->get_eeprom,
@@ -1052,7 +1053,8 @@ static int ethtool_set_eeprom(struct net_device *dev, void __user *useraddr)
 	u8 *data;
 	int ret = 0;
 
-	if (!ops->set_eeprom || !ops->get_eeprom_len)
+	if (!ops->set_eeprom || !ops->get_eeprom_len ||
+	    !ops->get_eeprom_len(dev))
 		return -EOPNOTSUPP;
 
 	if (copy_from_user(&eeprom, useraddr, sizeof(eeprom)))
-- 
1.9.1

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