ethtool: check device is present when getting link settings

[ Upstream commit a699781 ] A sysfs reader can race with a device reset or removal, attempting to read device state when the device is not actually present. eg: [exception RIP: qed_get_current_link+17] frank-w#8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede] frank-w#9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3 frank-w#10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4 frank-w#11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300 frank-w#12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c frank-w#13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b frank-w#14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3 frank-w#15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1 frank-w#16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f frank-w#17 [ffffb9e4f2907f38] do_syscall_64 at ffffffff98a052fb crash> struct net_device.state ffff9a9d21336000 state = 5, state 5 is __LINK_STATE_START (0b1) and __LINK_STATE_NOCARRIER (0b100). The device is not present, note lack of __LINK_STATE_PRESENT (0b10). This is the same sort of panic as observed in commit 4224cfd ("net-sysfs: add check for netdevice being present to speed_show"). There are many other callers of __ethtool_get_link_ksettings() which don't have a device presence check. Move this check into ethtool to protect all callers. Fixes: d519e17 ("net: export device speed and duplex via sysfs") Fixes: 4224cfd ("net-sysfs: add check for netdevice being present to speed_show") Signed-off-by: Jamie Bainbridge <[email protected]> Link: https://patch.msgid.link/8bae218864beaa44ed01628140475b9bf641c5b0.1724393671.git.jamie.bainbridge@gmail.com Signed-off-by: Jakub Kicinski <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
BtbN · Sep 4, 2024 · 1d6d9b5 · 1d6d9b5
1 parent 3c2f4db
commit 1d6d9b5
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diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
@@ -235,7 +235,7 @@ static ssize_t speed_show(struct device *dev,
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (netif_running(netdev) && netif_device_present(netdev)) {
+	if (netif_running(netdev)) {
 		struct ethtool_link_ksettings cmd;
 
 		if (!__ethtool_get_link_ksettings(netdev, &cmd))

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
@@ -441,6 +441,9 @@ int __ethtool_get_link_ksettings(struct net_device *dev,
 	if (!dev->ethtool_ops->get_link_ksettings)
 		return -EOPNOTSUPP;
 
+	if (!netif_device_present(dev))
+		return -ENODEV;
+
 	memset(link_ksettings, 0, sizeof(*link_ksettings));
 	return dev->ethtool_ops->get_link_ksettings(dev, link_ksettings);
 }