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authorEric Dumazet <edumazet@google.com>2014-09-04 09:21:56 +0400
committerDavid S. Miller <davem@davemloft.net>2014-09-06 04:15:50 +0400
commitcaa415270c732505240bb60171c44a7838c555e8 (patch)
treecd44cd81f85c3904340f5cef1a359e2ae97a0c20 /net/ipv4/fib_semantics.c
parent29abe2fda54f8e16ecff5d76d96325f31508d5ba (diff)
downloadlinux-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>
Diffstat (limited to 'net/ipv4/fib_semantics.c')
-rw-r--r--net/ipv4/fib_semantics.c8
1 files changed, 5 insertions, 3 deletions
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);