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authorPavel Emelyanov <xemul@openvz.org>2008-02-23 19:57:02 -0800
committerDavid S. Miller <davem@davemloft.net>2008-02-23 19:57:02 -0800
commitbc4bf5f38cf0a623e6a29f52ec80bfcc56a373c6 (patch)
tree44c9dab22f5d75d797845b54df07bd6da40bcc7e
parent1840bb13c22f5b8fd2e242e36c8d6ea3f312be67 (diff)
downloadlinux-stericsson-bc4bf5f38cf0a623e6a29f52ec80bfcc56a373c6.tar.gz
[NEIGH]: Fix race between neighbor lookup and table's hash_rnd update.
The neigh_hash_grow() may update the tbl->hash_rnd value, which is used in all tbl->hash callbacks to calculate the hashval. Two lookup routines may race with this, since they call the ->hash callback without the tbl->lock held. Since the hash_rnd is changed with this lock write-locked moving the calls to ->hash under this lock read-locked closes this gap. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/neighbour.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4062b88bfc1b..2328acbd16cd 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -358,11 +358,12 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
{
struct neighbour *n;
int key_len = tbl->key_len;
- u32 hash_val = tbl->hash(pkey, dev);
+ u32 hash_val;
NEIGH_CACHE_STAT_INC(tbl, lookups);
read_lock_bh(&tbl->lock);
+ hash_val = tbl->hash(pkey, dev);
for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
neigh_hold(n);
@@ -379,11 +380,12 @@ struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
{
struct neighbour *n;
int key_len = tbl->key_len;
- u32 hash_val = tbl->hash(pkey, NULL);
+ u32 hash_val;
NEIGH_CACHE_STAT_INC(tbl, lookups);
read_lock_bh(&tbl->lock);
+ hash_val = tbl->hash(pkey, NULL);
for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
if (!memcmp(n->primary_key, pkey, key_len) &&
(net == n->dev->nd_net)) {