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Commit 8c171d6c authored by Felix Jia's avatar Felix Jia Committed by David S. Miller
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net/ipv6: avoid possible dead locking on addr_gen_mode sysctl 



The addr_gen_mode variable can be accessed by both sysctl and netlink.
Repleacd rtnl_lock() with rtnl_trylock() protect the sysctl operation to
avoid the possbile dead lock.`

Signed-off-by: default avatarFelix Jia <felix.jia@alliedtelesis.co.nz>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a3695e97

net/ipv6/addrconf.c

+15 −7
Original line number Diff line number Diff line
@@ -5692,13 +5692,18 @@ static int addrconf_sysctl_addr_gen_mode(struct ctl_table *ctl, int write, 
	struct inet6_dev *idev = (struct inet6_dev *)ctl->extra1;

	struct net *net = (struct net *)ctl->extra2;



	if (!rtnl_trylock())

		return restart_syscall();



	ret = proc_dointvec(ctl, write, buffer, lenp, ppos);



	if (write) {

		new_val = *((int *)ctl->data);



		if (check_addr_gen_mode(new_val) < 0)

			return -EINVAL;

		if (check_addr_gen_mode(new_val) < 0) {

			ret = -EINVAL;

			goto out;

		}



		/* request for default */

		if (&net->ipv6.devconf_dflt->addr_gen_mode == ctl->data) {
@@ -5707,20 +5712,23 @@ static int addrconf_sysctl_addr_gen_mode(struct ctl_table *ctl, int write, 
		/* request for individual net device */

		} else {

			if (!idev)

				return ret;

				goto out;



			if (check_stable_privacy(idev, net, new_val) < 0)

				return -EINVAL;

			if (check_stable_privacy(idev, net, new_val) < 0) {

				ret = -EINVAL;

				goto out;

			}



			if (idev->cnf.addr_gen_mode != new_val) {

				idev->cnf.addr_gen_mode = new_val;

				rtnl_lock();

				addrconf_dev_config(idev->dev);

				rtnl_unlock();

			}

		}

	}



out:

	rtnl_unlock();



	return ret;

}