5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jamie Bainbridge <jamie.bainbridge@xxxxxxxxx>
[ Upstream commit a699781c79ecf6cfe67fb00a0331b4088c7c8466 ]
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]
#8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede]
#9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3
#10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4
#11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300
#12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c
#13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b
#14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3
#15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1
#16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f
#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 4224cfd7fb65
("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: d519e17e2d01 ("net: export device speed and duplex via sysfs")
Fixes: 4224cfd7fb65 ("net-sysfs: add check for netdevice being present to speed_show")
Signed-off-by: Jamie Bainbridge <jamie.bainbridge@xxxxxxxxx>
Link: https://patch.msgid.link/8bae218864beaa44ed01628140475b9bf641c5b0.1724393671.git.jamie.bainbridge@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/ethtool.c | 3 +++
net/core/net-sysfs.c | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 9ae38c3e2bf0a..f0346cf4462e0 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -549,6 +549,9 @@ 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);
}
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index ad45f13a0370b..bcad7028bbf45 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -212,7 +212,7 @@ 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))
--
2.43.0
