* [PATCH net-next] ipv4: fix a race in update_or_create_fnhe()
@ 2014-09-04 5:21 Eric Dumazet
2014-09-06 0:16 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2014-09-04 5:21 UTC (permalink / raw)
To: David Miller; +Cc: netdev
From: Eric Dumazet <edumazet@google.com>
nh_exceptions is effectively used under rcu, but lacks proper
barriers. Between kzalloc() and setting of nh->nh_exceptions(),
we need a proper memory barrier.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 4895c771c7f00 ("ipv4: Add FIB nexthop exceptions.")
---
include/net/ip_fib.h | 2 +-
net/ipv4/fib_semantics.c | 8 +++++---
net/ipv4/route.c | 6 +++---
3 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 9922093f575e..f30fd554127e 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -87,7 +87,7 @@ struct fib_nh {
int nh_saddr_genid;
struct rtable __rcu * __percpu *nh_pcpu_rth_output;
struct rtable __rcu *nh_rth_input;
- struct fnhe_hash_bucket *nh_exceptions;
+ struct fnhe_hash_bucket __rcu *nh_exceptions;
};
/*
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index b10cd43a4722..5b6efb3d2308 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -157,9 +157,12 @@ static void rt_fibinfo_free(struct rtable __rcu **rtp)
static void free_nh_exceptions(struct fib_nh *nh)
{
- struct fnhe_hash_bucket *hash = nh->nh_exceptions;
+ struct fnhe_hash_bucket *hash;
int i;
+ hash = rcu_dereference_protected(nh->nh_exceptions, 1);
+ if (!hash)
+ return;
for (i = 0; i < FNHE_HASH_SIZE; i++) {
struct fib_nh_exception *fnhe;
@@ -205,8 +208,7 @@ static void free_fib_info_rcu(struct rcu_head *head)
change_nexthops(fi) {
if (nexthop_nh->nh_dev)
dev_put(nexthop_nh->nh_dev);
- if (nexthop_nh->nh_exceptions)
- free_nh_exceptions(nexthop_nh);
+ free_nh_exceptions(nexthop_nh);
rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
rt_fibinfo_free(&nexthop_nh->nh_rth_input);
} endfor_nexthops(fi);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index eaa4b000c7b4..44b0cbdd76f1 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -628,12 +628,12 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
spin_lock_bh(&fnhe_lock);
- hash = nh->nh_exceptions;
+ hash = rcu_dereference(nh->nh_exceptions);
if (!hash) {
hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
if (!hash)
goto out_unlock;
- nh->nh_exceptions = hash;
+ rcu_assign_pointer(nh->nh_exceptions, hash);
}
hash += hval;
@@ -1242,7 +1242,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst)
static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
{
- struct fnhe_hash_bucket *hash = nh->nh_exceptions;
+ struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
struct fib_nh_exception *fnhe;
u32 hval;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next] ipv4: fix a race in update_or_create_fnhe()
2014-09-04 5:21 [PATCH net-next] ipv4: fix a race in update_or_create_fnhe() Eric Dumazet
@ 2014-09-06 0:16 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2014-09-06 0:16 UTC (permalink / raw)
To: eric.dumazet; +Cc: netdev
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 03 Sep 2014 22:21:56 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> nh_exceptions is effectively used under rcu, but lacks proper
> barriers. Between kzalloc() and setting of nh->nh_exceptions(),
> we need a proper memory barrier.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Fixes: 4895c771c7f00 ("ipv4: Add FIB nexthop exceptions.")
Applied, thanks Eric.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2014-09-06 0:16 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-09-04 5:21 [PATCH net-next] ipv4: fix a race in update_or_create_fnhe() Eric Dumazet
2014-09-06 0:16 ` David Miller
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.