inet 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 disabled 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@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 4ed429b..0546a0b 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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);