From 073862ba5d249c20bd5c49fc6d904ff0e1f6a672 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 26 Jan 2012 00:41:38 +0000 Subject: [PATCH] netns: fix net_alloc_generic() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When a new net namespace is created, we should attach to it a "struct net_generic" with enough slots (even empty), or we can hit the following BUG_ON() : [ 200.752016] kernel BUG at include/net/netns/generic.h:40! ... [ 200.752016] [] ? get_cfcnfg+0x3a/0x180 [ 200.752016] [] ? lockdep_rtnl_is_held+0x10/0x20 [ 200.752016] [] caif_device_notify+0x2e/0x530 [ 200.752016] [] notifier_call_chain+0x67/0x110 [ 200.752016] [] raw_notifier_call_chain+0x11/0x20 [ 200.752016] [] call_netdevice_notifiers+0x32/0x60 [ 200.752016] [] register_netdevice+0x196/0x300 [ 200.752016] [] register_netdev+0x19/0x30 [ 200.752016] [] loopback_net_init+0x4a/0xa0 [ 200.752016] [] ops_init+0x42/0x180 [ 200.752016] [] setup_net+0x6b/0x100 [ 200.752016] [] copy_net_ns+0x86/0x110 [ 200.752016] [] create_new_namespaces+0xd9/0x190 net_alloc_generic() should take into account the maximum index into the ptr array, as a subsystem might use net_generic() anytime. This also reduces number of reallocations in net_assign_generic() Reported-by: Sasha Levin Tested-by: Sasha Levin Signed-off-by: Eric Dumazet Cc: Sjur Brændeland Cc: Eric W. Biederman Cc: Pavel Emelyanov Signed-off-by: David S. Miller --- net/core/net_namespace.c | 31 ++++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-) diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index aefcd7acbffa..0e950fda9a0a 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -30,6 +30,20 @@ EXPORT_SYMBOL(init_net); #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ +static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS; + +static struct net_generic *net_alloc_generic(void) +{ + struct net_generic *ng; + size_t generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]); + + ng = kzalloc(generic_size, GFP_KERNEL); + if (ng) + ng->len = max_gen_ptrs; + + return ng; +} + static int net_assign_generic(struct net *net, int id, void *data) { struct net_generic *ng, *old_ng; @@ -43,8 +57,7 @@ static int net_assign_generic(struct net *net, int id, void *data) if (old_ng->len >= id) goto assign; - ng = kzalloc(sizeof(struct net_generic) + - id * sizeof(void *), GFP_KERNEL); + ng = net_alloc_generic(); if (ng == NULL) return -ENOMEM; @@ -59,7 +72,6 @@ static int net_assign_generic(struct net *net, int id, void *data) * the old copy for kfree after a grace period. */ - ng->len = id; memcpy(&ng->ptr, &old_ng->ptr, old_ng->len * sizeof(void*)); rcu_assign_pointer(net->gen, ng); @@ -161,18 +173,6 @@ out_undo: goto out; } -static struct net_generic *net_alloc_generic(void) -{ - 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; -} #ifdef CONFIG_NET_NS static struct kmem_cache *net_cachep; @@ -483,6 +483,7 @@ again: } return error; } + max_gen_ptrs = max_t(unsigned int, max_gen_ptrs, *ops->id); } error = __register_pernet_operations(list, ops); if (error) { -- 2.20.1