From 193f3685d0546b0cea20c99894aadb70098e47bf Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 21 Feb 2019 11:19:41 +0100 Subject: [PATCH] ipv6: route: enforce RCU protection in rt6_update_exception_stamp_rt() We must access rt6_info->from under RCU read lock: move the dereference under such lock, with proper annotation. v1 -> v2: - avoid using multiple, racy, fetch operations for rt->from Fixes: a68886a69180 ("net/ipv6: Make from in rt6_info rcu protected") Signed-off-by: Paolo Abeni Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/ipv6/route.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 964491cf3672..2b1ed8c6fcab 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1599,15 +1599,15 @@ static int rt6_remove_exception_rt(struct rt6_info *rt) static void rt6_update_exception_stamp_rt(struct rt6_info *rt) { struct rt6_exception_bucket *bucket; - struct fib6_info *from = rt->from; struct in6_addr *src_key = NULL; struct rt6_exception *rt6_ex; - - if (!from || - !(rt->rt6i_flags & RTF_CACHE)) - return; + struct fib6_info *from; rcu_read_lock(); + from = rcu_dereference(rt->from); + if (!from || !(rt->rt6i_flags & RTF_CACHE)) + goto unlock; + bucket = rcu_dereference(from->rt6i_exception_bucket); #ifdef CONFIG_IPV6_SUBTREES @@ -1626,6 +1626,7 @@ static void rt6_update_exception_stamp_rt(struct rt6_info *rt) if (rt6_ex) rt6_ex->stamp = jiffies; +unlock: rcu_read_unlock(); } -- 2.34.1