| Message ID | 6c6b2fecaf381b25ec8d5ecc4e30ff2a186cad48.1722925756.git.jamie.bainbridge@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v4] net-sysfs: check device is present when showing duplex | expand |
On Tue, 6 Aug 2024 16:35:27 +1000 Jamie Bainbridge wrote: > A sysfs reader can race with a device reset or removal, attempting to > read device state when the device is not actually present. True, but.. > - if (netif_running(netdev)) { > + if (netif_running(netdev) && netif_device_present(netdev)) { > struct ethtool_link_ksettings cmd; > > if (!__ethtool_get_link_ksettings(netdev, &cmd)) { ..there are more callers of __ethtool_get_link_ksettings() and only a fraction of them have something resembling a presence check in their path. Can we put the check inside __ethtool_get_link_ksettings() itself?
On Fri, 9 Aug 2024 at 01:10, Jakub Kicinski <kuba@kernel.org> wrote: > > On Tue, 6 Aug 2024 16:35:27 +1000 Jamie Bainbridge wrote: > > A sysfs reader can race with a device reset or removal, attempting to > > read device state when the device is not actually present. > > True, but.. > > > - if (netif_running(netdev)) { > > + if (netif_running(netdev) && netif_device_present(netdev)) { > > struct ethtool_link_ksettings cmd; > > > > if (!__ethtool_get_link_ksettings(netdev, &cmd)) { > > ..there are more callers of __ethtool_get_link_ksettings() and only > a fraction of them have something resembling a presence check in > their path. Can we put the check inside __ethtool_get_link_ksettings() > itself? No worries. iiuc that would also mean reverting commit 4224cfd7fb65 ("net-sysfs: add check for netdevice being present to speed_show") because the check is being centralised. Should I do that in the same patch, or a separate revert patch?
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 0e2084ce7b7572bff458ed7e02358d9258c74628..22801d165d852a6578ca625b9674090519937be5 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -261,7 +261,7 @@ static ssize_t duplex_show(struct device *dev, if (!rtnl_trylock()) return restart_syscall(); - if (netif_running(netdev)) { + if (netif_running(netdev) && netif_device_present(netdev)) { struct ethtool_link_ksettings cmd; if (!__ethtool_get_link_ksettings(netdev, &cmd)) {
A sysfs reader can race with a device reset or removal, attempting to read device state when the device is not actually present. This is the same sort of panic as observed in commit 4224cfd7fb65 ("net-sysfs: add check for netdevice being present to speed_show"): [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). Resolve by adding the same netif_device_present() check to duplex_show. Fixes: d519e17e2d01 ("net: export device speed and duplex via sysfs") 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. --- net/core/net-sysfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)