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net: ethtool: Fix suspicious rcu_dereference usage

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The __ethtool_get_ts_info function can be called with or without the
rtnl lock held. When the rtnl lock is not held, using rtnl_dereference()
triggers a warning due to the lack of lock context.

Add an rcu_read_lock() to ensure the lock is acquired and to maintain
synchronization.

Reported-by: syzbot+a344326c05c98ba19682@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/676147f8.050a0220.37aaf.0154.GAE@google.com/
Fixes: b9e3f7dc9e ("net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology")
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241220083741.175329-1-kory.maincent@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kory Maincent 2024-12-20 09:37:40 +01:00 • committed by Jakub Kicinski
parent 3f8f2e93cd
commit 4c61d809cf
1 changed files with 4 additions and 1 deletions
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5
net/ethtool/common.c
View file

@ -870,7 +870,8 @@ int __ethtool_get_ts_info(struct net_device *dev,
{
struct hwtstamp_provider *hwprov;
hwprov = rtnl_dereference(dev->hwprov);
rcu_read_lock();
hwprov = rcu_dereference(dev->hwprov);
/* No provider specified, use default behavior */
if (!hwprov) {
const struct ethtool_ops *ops = dev->ethtool_ops;
@ -887,9 +888,11 @@ int __ethtool_get_ts_info(struct net_device *dev,
info->so_timestamping |= SOF_TIMESTAMPING_RX_SOFTWARE |
SOF_TIMESTAMPING_SOFTWARE;
rcu_read_unlock();
return err;
}
rcu_read_unlock();
return ethtool_get_ts_info_by_phc(dev, info, &hwprov->desc);
}