tipc: fix node refcount issue
authorErik Hugne <erik.hugne@ericsson.com>
Thu, 23 Apr 2015 13:37:40 +0000 (09:37 -0400)
committerDavid S. Miller <davem@davemloft.net>
Thu, 23 Apr 2015 15:50:34 +0000 (11:50 -0400)
commit73a317377303b5ec14d4703d73ba87efffbb779d
tree4d84c6e1de1a3edb94f21d9730b9c23fc31eb7c8
parent9871b27f6705fc6e0ba633b136369a289b2bfb99
tipc: fix node refcount issue

When link statistics is dumped over netlink, we iterate over
the list of peer nodes and append each links statistics to
the netlink msg. In the case where the dump is resumed after
filling up a nlmsg, the node refcnt is decremented without
having been incremented previously which may cause the node
reference to be freed. When this happens, the following
info/stacktrace will be generated, followed by a crash or
undefined behavior.
We fix this by removing the erroneous call to tipc_node_put
inside the loop that iterates over nodes.

[  384.312303] INFO: trying to register non-static key.
[  384.313110] the code is fine but needs lockdep annotation.
[  384.313290] turning off the locking correctness validator.
[  384.313290] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.0.0+ #13
[  384.313290] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  384.313290]  ffff88003c6d0290 ffff88003cc03ca8 ffffffff8170adf1 0000000000000007
[  384.313290]  ffffffff82728730 ffff88003cc03d38 ffffffff810a6a6d 00000000001d7200
[  384.313290]  ffff88003c6d0ab0 ffff88003cc03ce8 0000000000000285 0000000000000001
[  384.313290] Call Trace:
[  384.313290]  <IRQ>  [<ffffffff8170adf1>] dump_stack+0x4c/0x65
[  384.313290]  [<ffffffff810a6a6d>] __lock_acquire+0xf3d/0xf50
[  384.313290]  [<ffffffff810a7375>] lock_acquire+0xd5/0x290
[  384.313290]  [<ffffffffa0043e8c>] ? link_timeout+0x1c/0x170 [tipc]
[  384.313290]  [<ffffffffa0043e70>] ? link_state_event+0x4e0/0x4e0 [tipc]
[  384.313290]  [<ffffffff81712890>] _raw_spin_lock_bh+0x40/0x80
[  384.313290]  [<ffffffffa0043e8c>] ? link_timeout+0x1c/0x170 [tipc]
[  384.313290]  [<ffffffffa0043e8c>] link_timeout+0x1c/0x170 [tipc]
[  384.313290]  [<ffffffff810c4698>] call_timer_fn+0xb8/0x490
[  384.313290]  [<ffffffff810c45e0>] ? process_timeout+0x10/0x10
[  384.313290]  [<ffffffff810c5a2c>] run_timer_softirq+0x21c/0x420
[  384.313290]  [<ffffffffa0043e70>] ? link_state_event+0x4e0/0x4e0 [tipc]
[  384.313290]  [<ffffffff8105a954>] __do_softirq+0xf4/0x630
[  384.313290]  [<ffffffff8105afdd>] irq_exit+0x5d/0x60
[  384.313290]  [<ffffffff8103ade1>] smp_apic_timer_interrupt+0x41/0x50
[  384.313290]  [<ffffffff817144a0>] apic_timer_interrupt+0x70/0x80
[  384.313290]  <EOI>  [<ffffffff8100db10>] ? default_idle+0x20/0x210
[  384.313290]  [<ffffffff8100db0e>] ? default_idle+0x1e/0x210
[  384.313290]  [<ffffffff8100e61a>] arch_cpu_idle+0xa/0x10
[  384.313290]  [<ffffffff81099803>] cpu_startup_entry+0x2c3/0x530
[  384.313290]  [<ffffffff810d2893>] ? clockevents_register_device+0x113/0x200
[  384.313290]  [<ffffffff81038b0f>] start_secondary+0x13f/0x170

Fixes: 8a0f6ebe8494 ("tipc: involve reference counter for node structure")
Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/tipc/link.c