netdev - [PATCH net-next-2.6] net: sysfs: ethtool

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Date:	Mon, 26 Oct 2009 12:23:33 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"David S. Miller" <davem@...emloft.net>
CC:	Linux Netdev List <netdev@...r.kernel.org>,
	Andy Gospodarek <andy@...yhouse.net>
Subject: [PATCH net-next-2.6]  net: sysfs: ethtool_ops can be NULL

commit d519e17e2d01a0ee9abe083019532061b4438065
(net: export device speed and duplex via sysfs)
made the wrong assumption that netdev->ethtool_ops was always set.

This makes possible to crash kernel and let rtnl in locked state.

modprobe dummy
ip link set dummy0 up
(udev runs and crash)

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
 net/core/net-sysfs.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 753c420..89de182 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -139,7 +139,9 @@ static ssize_t show_speed(struct device *dev,
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (netif_running(netdev) && netdev->ethtool_ops->get_settings) {
+	if (netif_running(netdev) &&
+	    netdev->ethtool_ops &&
+	    netdev->ethtool_ops->get_settings) {
 		struct ethtool_cmd cmd = { ETHTOOL_GSET };
 
 		if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
@@ -158,7 +160,9 @@ static ssize_t show_duplex(struct device *dev,
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (netif_running(netdev) && netdev->ethtool_ops->get_settings) {
+	if (netif_running(netdev) &&
+	    netdev->ethtool_ops &&
+	    netdev->ethtool_ops->get_settings) {
 		struct ethtool_cmd cmd = { ETHTOOL_GSET };
 
 		if (!netdev->ethtool_ops->get_settings(netdev, &cmd))
--
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