From 66d95b6705a6347f7b2645e042874ec0bb03b726 Mon Sep 17 00:00:00 2001 From: Ying Xue Date: Wed, 15 Jun 2016 14:10:57 +0800 Subject: [PATCH] tipc: fix suspicious RCU usage When run tipcTS&tipcTC test suite, the following complaint appears: [ 56.926168] =============================== [ 56.926169] [ INFO: suspicious RCU usage. ] [ 56.926171] 4.7.0-rc1+ #160 Not tainted [ 56.926173] ------------------------------- [ 56.926174] net/tipc/bearer.c:408 suspicious rcu_dereference_protected() usage! [ 56.926175] [ 56.926175] other info that might help us debug this: [ 56.926175] [ 56.926177] [ 56.926177] rcu_scheduler_active = 1, debug_locks = 1 [ 56.926179] 3 locks held by swapper/4/0: [ 56.926180] #0: (((&req->timer))){+.-...}, at: [] call_timer_fn+0x5/0x340 [ 56.926203] #1: (&(&req->lock)->rlock){+.-...}, at: [] disc_timeout+0x1b/0xd0 [tipc] [ 56.926212] #2: (rcu_read_lock){......}, at: [] tipc_bearer_xmit_skb+0xb0/0x2e0 [tipc] [ 56.926218] [ 56.926218] stack backtrace: [ 56.926221] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 4.7.0-rc1+ #160 [ 56.926222] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 [ 56.926224] 0000000000000000 ffff880016803d28 ffffffff813c4423 ffff8800154252c0 [ 56.926227] 0000000000000001 ffff880016803d58 ffffffff810b7512 ffff8800124d8120 [ 56.926230] ffff880013f8a160 ffff8800132b5ccc ffff8800124d8120 ffff880016803d88 [ 56.926234] Call Trace: [ 56.926235] [] dump_stack+0x67/0x94 [ 56.926250] [] lockdep_rcu_suspicious+0xe2/0x120 [ 56.926256] [] tipc_l2_send_msg+0x131/0x1c0 [tipc] [ 56.926261] [] tipc_bearer_xmit_skb+0x14c/0x2e0 [tipc] [ 56.926266] [] ? tipc_bearer_xmit_skb+0xb0/0x2e0 [tipc] [ 56.926273] [] ? tipc_disc_init_msg+0x1f0/0x1f0 [tipc] [ 56.926278] [] ? tipc_disc_init_msg+0x1f0/0x1f0 [tipc] [ 56.926283] [] disc_timeout+0x56/0xd0 [tipc] [ 56.926288] [] call_timer_fn+0xb8/0x340 [ 56.926291] [] ? call_timer_fn+0x5/0x340 [ 56.926296] [] ? tipc_disc_init_msg+0x1f0/0x1f0 [tipc] [ 56.926300] [] run_timer_softirq+0x23a/0x390 [ 56.926306] [] ? clockevents_program_event+0x7f/0x130 [ 56.926316] [] __do_softirq+0xc3/0x4a2 [ 56.926323] [] irq_exit+0x8a/0xb0 [ 56.926327] [] smp_apic_timer_interrupt+0x46/0x60 [ 56.926331] [] apic_timer_interrupt+0x89/0x90 [ 56.926333] [] ? default_idle+0x2a/0x1a0 [ 56.926340] [] ? default_idle+0x28/0x1a0 [ 56.926342] [] arch_cpu_idle+0xf/0x20 [ 56.926345] [] default_idle_call+0x2f/0x50 [ 56.926347] [] cpu_startup_entry+0x215/0x3e0 [ 56.926353] [] start_secondary+0xf9/0x100 The warning appears as rtnl_dereference() is wrongly used in tipc_l2_send_msg() under RCU read lock protection. Instead the proper usage should be that rcu_dereference_rtnl() is called here. Fixes: 5b7066c3dd24 ("tipc: stricter filtering of packets in bearer layer") Acked-by: Jon Maloy Signed-off-by: Ying Xue Signed-off-by: David S. Miller --- net/tipc/bearer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 6f11c62bc8f9..bf8f05c3eb82 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -405,7 +405,7 @@ int tipc_l2_send_msg(struct net *net, struct sk_buff *skb, return 0; /* Send RESET message even if bearer is detached from device */ - tipc_ptr = rtnl_dereference(dev->tipc_ptr); + tipc_ptr = rcu_dereference_rtnl(dev->tipc_ptr); if (unlikely(!tipc_ptr && !msg_is_reset(buf_msg(skb)))) goto drop; -- 2.20.1