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ipv6: route: enforce RCU protection in ip6_route_check_nh_onlink()

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We need a RCU critical section around rt6_info->from deference, and
proper annotation.

Fixes: 4ed591c8ab ("net/ipv6: Allow onlink routes to have a device mismatch if it is the default route")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2019-02-21 11:19:42 +01:00 committed by David S. Miller
parent 193f3685d0
commit bf1dc8bad1
1 changed files with 5 additions and 1 deletions
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6
net/ipv6/route.c
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@ -2743,20 +2743,24 @@ static int ip6_route_check_nh_onlink(struct net *net,
u32 tbid = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
const struct in6_addr *gw_addr = &cfg->fc_gateway;
u32 flags = RTF_LOCAL | RTF_ANYCAST | RTF_REJECT;
struct fib6_info *from;
struct rt6_info *grt;
int err;
err = 0;
grt = ip6_nh_lookup_table(net, cfg, gw_addr, tbid, 0);
if (grt) {
rcu_read_lock();
from = rcu_dereference(grt->from);
if (!grt->dst.error &&
/* ignore match if it is the default route */
grt->from && !ipv6_addr_any(&grt->from->fib6_dst.addr) &&
from && !ipv6_addr_any(&from->fib6_dst.addr) &&
(grt->rt6i_flags & flags || dev != grt->dst.dev)) {
NL_SET_ERR_MSG(extack,
"Nexthop has invalid gateway or device mismatch");
err = -EINVAL;
}
rcu_read_unlock();
ip6_rt_put(grt);
}