| Message ID | 20170810145302.30391-4-fw@strlen.de |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On 8/10/17 8:52 AM, Florian Westphal wrote: > David Ahern reports following splat: > RTNL: assertion failed at net/core/dev.c (5717) > netdev_master_upper_dev_get+0x5f/0x70 > if_nlmsg_size+0x158/0x240 > rtnl_calcit.isra.26+0xa3/0xf0 > > rtnl_link_get_slave_info_data_size currently assumes RTNL protection, but > there appears to be no hard requirement for this, so use rcu instead. > > At the time of this writing, there are three 'get_slave_size' callbacks > (now invoked under rcu): bond_get_slave_size, vrf_get_slave_size and > br_port_get_slave_size, all return constant only (i.e. they don't sleep). > > Fixes: 6853dd488119 ("rtnetlink: protect handler table with rcu") > Reported-by: David Ahern <dsahern@gmail.com> > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > net/core/rtnetlink.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) Acked-by: David Ahern <dsahern@gmail.com>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a9b5ebc1af21..087f2434813a 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -402,16 +402,24 @@ static size_t rtnl_link_get_slave_info_data_size(const struct net_device *dev) { struct net_device *master_dev; const struct rtnl_link_ops *ops; + size_t size = 0; - master_dev = netdev_master_upper_dev_get((struct net_device *) dev); + rcu_read_lock(); + + master_dev = netdev_master_upper_dev_get_rcu((struct net_device *)dev); if (!master_dev) - return 0; + goto out; + ops = master_dev->rtnl_link_ops; if (!ops || !ops->get_slave_size) - return 0; + goto out; /* IFLA_INFO_SLAVE_DATA + nested data */ - return nla_total_size(sizeof(struct nlattr)) + + size = nla_total_size(sizeof(struct nlattr)) + ops->get_slave_size(master_dev, dev); + +out: + rcu_read_unlock(); + return size; } static size_t rtnl_link_get_size(const struct net_device *dev)
David Ahern reports following splat: RTNL: assertion failed at net/core/dev.c (5717) netdev_master_upper_dev_get+0x5f/0x70 if_nlmsg_size+0x158/0x240 rtnl_calcit.isra.26+0xa3/0xf0 rtnl_link_get_slave_info_data_size currently assumes RTNL protection, but there appears to be no hard requirement for this, so use rcu instead. At the time of this writing, there are three 'get_slave_size' callbacks (now invoked under rcu): bond_get_slave_size, vrf_get_slave_size and br_port_get_slave_size, all return constant only (i.e. they don't sleep). Fixes: 6853dd488119 ("rtnetlink: protect handler table with rcu") Reported-by: David Ahern <dsahern@gmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> --- net/core/rtnetlink.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)