4.19-stable review patch. If anyone has any objections, please let me know.
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From: Taehee Yoo ap420073@gmail.com
commit 2a61d8b883bbad26b06d2e6cc3777a697e78830d upstream.
A proc_remove() can sleep. so that it can't be inside of spin_lock. Hence proc_remove() is moved to outside of spin_lock. and it also adds mutex to sync create and remove of proc entry(config->pde).
test commands: SHELL#1 %while :; do iptables -A INPUT -p udp -i enp2s0 -d 192.168.1.100 \ --dport 9000 -j CLUSTERIP --new --hashmode sourceip \ --clustermac 01:00:5e:00:00:21 --total-nodes 3 --local-node 3; \ iptables -F; done
SHELL#2 %while :; do echo +1 > /proc/net/ipt_CLUSTERIP/192.168.1.100; \ echo -1 > /proc/net/ipt_CLUSTERIP/192.168.1.100; done
[ 2949.569864] BUG: sleeping function called from invalid context at kernel/sched/completion.c:99 [ 2949.579944] in_atomic(): 1, irqs_disabled(): 0, pid: 5472, name: iptables [ 2949.587920] 1 lock held by iptables/5472: [ 2949.592711] #0: 000000008f0ebcf2 (&(&cn->lock)->rlock){+...}, at: refcount_dec_and_lock+0x24/0x50 [ 2949.603307] CPU: 1 PID: 5472 Comm: iptables Tainted: G W 4.19.0-rc5+ #16 [ 2949.604212] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015 [ 2949.604212] Call Trace: [ 2949.604212] dump_stack+0xc9/0x16b [ 2949.604212] ? show_regs_print_info+0x5/0x5 [ 2949.604212] ___might_sleep+0x2eb/0x420 [ 2949.604212] ? set_rq_offline.part.87+0x140/0x140 [ 2949.604212] ? _rcu_barrier_trace+0x400/0x400 [ 2949.604212] wait_for_completion+0x94/0x710 [ 2949.604212] ? wait_for_completion_interruptible+0x780/0x780 [ 2949.604212] ? __kernel_text_address+0xe/0x30 [ 2949.604212] ? __lockdep_init_map+0x10e/0x5c0 [ 2949.604212] ? __lockdep_init_map+0x10e/0x5c0 [ 2949.604212] ? __init_waitqueue_head+0x86/0x130 [ 2949.604212] ? init_wait_entry+0x1a0/0x1a0 [ 2949.604212] proc_entry_rundown+0x208/0x270 [ 2949.604212] ? proc_reg_get_unmapped_area+0x370/0x370 [ 2949.604212] ? __lock_acquire+0x4500/0x4500 [ 2949.604212] ? complete+0x18/0x70 [ 2949.604212] remove_proc_subtree+0x143/0x2a0 [ 2949.708655] ? remove_proc_entry+0x390/0x390 [ 2949.708655] clusterip_tg_destroy+0x27a/0x630 [ipt_CLUSTERIP] [ ... ]
Fixes: b3e456fce9f5 ("netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation") Signed-off-by: Taehee Yoo ap420073@gmail.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv4/netfilter/ipt_CLUSTERIP.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -56,7 +56,7 @@ struct clusterip_config { #endif enum clusterip_hashmode hash_mode; /* which hashing mode */ u_int32_t hash_initval; /* hash initialization */ - struct rcu_head rcu; + struct rcu_head rcu; /* for call_rcu_bh */ struct net *net; /* netns for pernet list */ char ifname[IFNAMSIZ]; /* device ifname */ }; @@ -72,6 +72,8 @@ struct clusterip_net {
#ifdef CONFIG_PROC_FS struct proc_dir_entry *procdir; + /* mutex protects the config->pde*/ + struct mutex mutex; #endif };
@@ -118,17 +120,18 @@ clusterip_config_entry_put(struct cluste
local_bh_disable(); if (refcount_dec_and_lock(&c->entries, &cn->lock)) { + list_del_rcu(&c->list); + spin_unlock(&cn->lock); + local_bh_enable(); /* In case anyone still accesses the file, the open/close * functions are also incrementing the refcount on their own, * so it's safe to remove the entry even if it's in use. */ #ifdef CONFIG_PROC_FS + mutex_lock(&cn->mutex); if (cn->procdir) proc_remove(c->pde); + mutex_unlock(&cn->mutex); #endif - list_del_rcu(&c->list); - spin_unlock(&cn->lock); - local_bh_enable(); - return; } local_bh_enable(); @@ -278,9 +281,11 @@ clusterip_config_init(struct net *net, c
/* create proc dir entry */ sprintf(buffer, "%pI4", &ip); + mutex_lock(&cn->mutex); c->pde = proc_create_data(buffer, 0600, cn->procdir, &clusterip_proc_fops, c); + mutex_unlock(&cn->mutex); if (!c->pde) { err = -ENOMEM; goto err; @@ -833,6 +838,7 @@ static int clusterip_net_init(struct net pr_err("Unable to proc dir entry\n"); return -ENOMEM; } + mutex_init(&cn->mutex); #endif /* CONFIG_PROC_FS */
return 0; @@ -841,9 +847,12 @@ static int clusterip_net_init(struct net static void clusterip_net_exit(struct net *net) { struct clusterip_net *cn = clusterip_pernet(net); + #ifdef CONFIG_PROC_FS + mutex_lock(&cn->mutex); proc_remove(cn->procdir); cn->procdir = NULL; + mutex_unlock(&cn->mutex); #endif nf_unregister_net_hook(net, &cip_arp_ops); }