Commit 4c61d809 authored by Kory Maincent's avatar Kory Maincent Committed by Jakub Kicinski
Browse files

net: ethtool: Fix suspicious rcu_dereference usage 



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: default avatar <syzbot+a344326c05c98ba19682@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/netdev/676147f8.050a0220.37aaf.0154.GAE@google.com/


Fixes: b9e3f7dc ("net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology")
Signed-off-by: default avatarKory Maincent <kory.maincent@bootlin.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241220083741.175329-1-kory.maincent@bootlin.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 3f8f2e93

net/ethtool/common.c

+4 −1
Original line number Diff line number Diff line
@@ -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);

}