From 193f3685d0546b0cea20c99894aadb70098e47bf Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
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 <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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 964491cf36720..2b1ed8c6fcabc 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();
}
--
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