diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-09-04 09:21:56 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-06 04:15:50 +0400 |
| commit | caa415270c732505240bb60171c44a7838c555e8 (patch) | |
| tree | cd44cd81f85c3904340f5cef1a359e2ae97a0c20 | |
| parent | 29abe2fda54f8e16ecff5d76d96325f31508d5ba (diff) | |
| download | linux-caa415270c732505240bb60171c44a7838c555e8.tar.xz | |
ipv4: fix a race in update_or_create_fnhe()
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.")
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/ip_fib.h | 2 | ||||
| -rw-r--r-- | net/ipv4/fib_semantics.c | 8 | ||||
| -rw-r--r-- | 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; |