netdev - [PATCH][NEIGH]: Fix race between neighbor lookup and table's hash

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 22 Feb 2008 12:37:03 +0300
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	David Miller <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>, devel@...nvz.org
Subject: [PATCH][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@...nvz.org>

---

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4062b88..2328acb 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)) {
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html