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Date: Tue, 24 Jun 2008 14:43:17 +0400
From: Pavel Emelyanov <xemul@...nvz.org>
To: David Miller <davem@...emloft.net>,
Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH (regression)] Fragments: fix race between inet_frag_find and
inet_frag_secret_rebuild
The problem is that while we work w/o the inet_frags.lock even
read-locked the secret rebuild timer may occur (on another CPU,
since BHs are still disables in the inet_frag_find) and change
the rnd seed for ipv4/6 fragments.
It was caused by my patch fd9e63544cac30a34c951f0ec958038f0529e244
([INET]: Omit double hash calculations in xxx_frag_intern) late
in the 2.6.24 kernel, so this should probably be queued to -stable.
Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
---
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 4ed429b..0546a0b 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -192,14 +192,21 @@ EXPORT_SYMBOL(inet_frag_evictor);
static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
struct inet_frag_queue *qp_in, struct inet_frags *f,
- unsigned int hash, void *arg)
+ void *arg)
{
struct inet_frag_queue *qp;
#ifdef CONFIG_SMP
struct hlist_node *n;
#endif
+ unsigned int hash;
write_lock(&f->lock);
+ /*
+ * While we stayed w/o the lock other CPU could update
+ * the rnd seed, so we need to re-calculate the hash
+ * chain. Fortunatelly the qp_in can be used to get one.
+ */
+ hash = f->hashfn(qp_in);
#ifdef CONFIG_SMP
/* With SMP race we have to recheck hash table, because
* such entry could be created on other cpu, while we
@@ -247,7 +254,7 @@ static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
}
static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
- struct inet_frags *f, void *arg, unsigned int hash)
+ struct inet_frags *f, void *arg)
{
struct inet_frag_queue *q;
@@ -255,7 +262,7 @@ static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
if (q == NULL)
return NULL;
- return inet_frag_intern(nf, q, f, hash, arg);
+ return inet_frag_intern(nf, q, f, arg);
}
struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
@@ -264,7 +271,6 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
struct inet_frag_queue *q;
struct hlist_node *n;
- read_lock(&f->lock);
hlist_for_each_entry(q, n, &f->hash[hash], list) {
if (q->net == nf && f->match(q, key)) {
atomic_inc(&q->refcnt);
@@ -274,6 +280,6 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
}
read_unlock(&f->lock);
- return inet_frag_create(nf, f, key, hash);
+ return inet_frag_create(nf, f, key);
}
EXPORT_SYMBOL(inet_frag_find);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index cd6ce6a..37221f6 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -229,6 +229,8 @@ static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user)
arg.iph = iph;
arg.user = user;
+
+ read_lock(&ip4_frags.lock);
hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash);
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index e65e26e..cf20bc4 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -207,9 +207,10 @@ fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
arg.id = id;
arg.src = src;
arg.dst = dst;
+
+ read_lock_bh(&nf_frags.lock);
hash = ip6qhashfn(id, src, dst);
- local_bh_disable();
q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash);
local_bh_enable();
if (q == NULL)
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 798cabc..a60d7d1 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -247,6 +247,8 @@ fq_find(struct net *net, __be32 id, struct in6_addr *src, struct in6_addr *dst,
arg.id = id;
arg.src = src;
arg.dst = dst;
+
+ read_lock(&ip6_frags.lock);
hash = ip6qhashfn(id, src, dst);
q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
--
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