From: Pavel Emelyanov Date: Sun, 24 Feb 2008 03:57:02 +0000 (-0800) Subject: [NEIGH]: Fix race between neighbor lookup and table's hash_rnd update. X-Git-Tag: v2.6.25-rc3~9^2~3 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=bc4bf5f38cf0a623e6a29f52ec80bfcc56a373c6;p=linux-2.6-omap-h63xx.git [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 Signed-off-by: David S. Miller --- diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 4062b88bfc1..2328acbd16c 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)) {