| Message ID | 8bae218864beaa44ed01628140475b9bf641c5b0.1724393671.git.jamie.bainbridge@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | a699781c79ecf6cfe67fb00a0331b4088c7c8466 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v5] ethtool: check device is present when getting link settings | expand |
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Fri, 23 Aug 2024 16:26:58 +1000 you wrote: > 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 > > [...] Here is the summary with links: - [net,v5] ethtool: check device is present when getting link settings https://git.kernel.org/netdev/net/c/a699781c79ec You are awesome, thank you!
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 0e2084ce7b7572bff458ed7e02358d9258c74628..444f23e74f8e6bed058eee09e03e045d4df6bd52 100644 --- 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 index e18823bf23306dffd32ddc752458e3c350a29b42..ae041f51cd2da4e6f98a1dc24ff109432dae2946 100644 --- a/net/ethtool/ioctl.c +++ b/net/ethtool/ioctl.c @@ -442,6 +442,9 @@ 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); }
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@gmail.com> --- v2: Restrict patch to just required path and describe problem in more detail as suggested by Johannes Berg. Improve commit message format as suggested by Shigeru Yoshida. v3: Use earlier Fixes commit as suggested by Paolo Abeni. v4: Typo as suggested by Simon Horman. v5: Move further up into ethtool as suggested by Jakub Kicinski. --- net/core/net-sysfs.c | 2 +- net/ethtool/ioctl.c | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-)