From 9a375803feaadb6c34e0807bd9325885dcca5c00 Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Fri, 27 Jun 2008 20:06:08 -0700 Subject: 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 Signed-off-by: David S. Miller --- net/ipv4/inet_fragment.c | 16 +++++++++++----- net/ipv4/ip_fragment.c | 2 ++ 2 files changed, 13 insertions(+), 5 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 4ed429bd595..0546a0bc97e 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 cd6ce6ac635..37221f65915 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); -- cgit v1.2.3-18-g5258