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ipv6: route: enforce RCU protection in rt6_update_exception_stamp_rt()

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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>
This commit is contained in:
Paolo Abeni 2019-02-21 11:19:41 +01:00 committed by David S. Miller
parent ae3b564179
commit 193f3685d0
1 changed files with 6 additions and 5 deletions
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11
net/ipv6/route.c
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@ -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) static void rt6_update_exception_stamp_rt(struct rt6_info *rt)
{ {
struct rt6_exception_bucket *bucket; struct rt6_exception_bucket *bucket;
struct fib6_info *from = rt->from;
struct in6_addr *src_key = NULL; struct in6_addr *src_key = NULL;
struct rt6_exception *rt6_ex; struct rt6_exception *rt6_ex;
struct fib6_info *from;
if (!from ||
!(rt->rt6i_flags & RTF_CACHE))
return;
rcu_read_lock(); rcu_read_lock();
from = rcu_dereference(rt->from);
if (!from || !(rt->rt6i_flags & RTF_CACHE))
goto unlock;
bucket = rcu_dereference(from->rt6i_exception_bucket); bucket = rcu_dereference(from->rt6i_exception_bucket);
#ifdef CONFIG_IPV6_SUBTREES #ifdef CONFIG_IPV6_SUBTREES
@ -1626,6 +1626,7 @@ static void rt6_update_exception_stamp_rt(struct rt6_info *rt)
if (rt6_ex) if (rt6_ex)
rt6_ex->stamp = jiffies; rt6_ex->stamp = jiffies;
unlock:
rcu_read_unlock(); rcu_read_unlock();
} }