From 486a87f1e5624096bd1c09e9e716239597d48dca Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Sun, 22 Feb 2009 00:07:53 -0800 Subject: netns: fix double free at netns creation This patch fix a double free when a network namespace fails. The previous code does a kfree of the net_generic structure when one of the init subsystem initialization fails. The 'setup_net' function does kfree(ng) and returns an error. The caller, 'copy_net_ns', call net_free on error, and this one calls kfree(net->gen), making this pointer freed twice. This patch make the code symetric, the net_alloc does the net_generic allocation and the net_free frees the net_generic. Signed-off-by: Daniel Lezcano Signed-off-by: David S. Miller --- net/core/net_namespace.c | 86 +++++++++++++++++++++++++++++++----------------- 1 file changed, 55 insertions(+), 31 deletions(-) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 55151fa..b0767ab 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -32,24 +32,14 @@ static __net_init int setup_net(struct net *net) { /* Must be called with net_mutex held */ struct pernet_operations *ops; - int error; - struct net_generic *ng; + int error = 0; atomic_set(&net->count, 1); + #ifdef NETNS_REFCNT_DEBUG atomic_set(&net->use_count, 0); #endif - error = -ENOMEM; - ng = kzalloc(sizeof(struct net_generic) + - INITIAL_NET_GEN_PTRS * sizeof(void *), GFP_KERNEL); - if (ng == NULL) - goto out; - - ng->len = INITIAL_NET_GEN_PTRS; - rcu_assign_pointer(net->gen, ng); - - error = 0; list_for_each_entry(ops, &pernet_list, list) { if (ops->init) { error = ops->init(net); @@ -70,7 +60,6 @@ out_undo: } rcu_barrier(); - kfree(ng); goto out; } @@ -78,16 +67,43 @@ out_undo: static struct kmem_cache *net_cachep; static struct workqueue_struct *netns_wq; -static struct net *net_alloc(void) +static struct net_generic *net_alloc_generic(void) { - return kmem_cache_zalloc(net_cachep, GFP_KERNEL); + struct net_generic *ng; + size_t generic_size = sizeof(struct net_generic) + + INITIAL_NET_GEN_PTRS * sizeof(void *); + + ng = kzalloc(generic_size, GFP_KERNEL); + if (ng) + ng->len = INITIAL_NET_GEN_PTRS; + + return ng; } -static void net_free(struct net *net) +static struct net *net_alloc(void) { + struct net *net = NULL; + struct net_generic *ng; + + ng = net_alloc_generic(); + if (!ng) + goto out; + + net = kmem_cache_zalloc(net_cachep, GFP_KERNEL); if (!net) - return; + goto out_free; + + rcu_assign_pointer(net->gen, ng); +out: + return net; + +out_free: + kfree(ng); + goto out; +} +static void net_free(struct net *net) +{ #ifdef NETNS_REFCNT_DEBUG if (unlikely(atomic_read(&net->use_count) != 0)) { printk(KERN_EMERG "network namespace not free! Usage: %d\n", @@ -112,27 +128,28 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net) err = -ENOMEM; new_net = net_alloc(); if (!new_net) - goto out; + goto out_err; mutex_lock(&net_mutex); err = setup_net(new_net); - if (err) - goto out_unlock; - - rtnl_lock(); - list_add_tail(&new_net->list, &net_namespace_list); - rtnl_unlock(); - - -out_unlock: + if (!err) { + rtnl_lock(); + list_add_tail(&new_net->list, &net_namespace_list); + rtnl_unlock(); + } mutex_unlock(&net_mutex); + + if (err) + goto out_free; out: put_net(old_net); - if (err) { - net_free(new_net); - new_net = ERR_PTR(err); - } return new_net; + +out_free: + net_free(new_net); +out_err: + new_net = ERR_PTR(err); + goto out; } static void cleanup_net(struct work_struct *work) @@ -188,6 +205,7 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net) static int __init net_ns_init(void) { + struct net_generic *ng; int err; printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net)); @@ -202,6 +220,12 @@ static int __init net_ns_init(void) panic("Could not create netns workq"); #endif + ng = net_alloc_generic(); + if (!ng) + panic("Could not allocate generic netns"); + + rcu_assign_pointer(init_net.gen, ng); + mutex_lock(&net_mutex); err = setup_net(&init_net); -- cgit v1.1