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a0efb80ce3
linux/net/sched
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WANG Cong a0efb80ce3 net_sched: avoid calling tcf_unbind_filter() in call_rcu callback 
This fixes the following crash:

[   63.976822] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[   63.980094] CPU: 1 PID: 15 Comm: ksoftirqd/1 Not tainted 3.17.0-rc6+ #648
[   63.980094] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   63.980094] task: ffff880117dea690 ti: ffff880117dfc000 task.ti: ffff880117dfc000
[   63.980094] RIP: 0010:[<ffffffff817e6d07>]  [<ffffffff817e6d07>] u32_destroy_key+0x27/0x6d
[   63.980094] RSP: 0018:ffff880117dffcc0  EFLAGS: 00010202
[   63.980094] RAX: ffff880117dea690 RBX: ffff8800d02e0820 RCX: 0000000000000000
[   63.980094] RDX: 0000000000000001 RSI: 0000000000000002 RDI: 6b6b6b6b6b6b6b6b
[   63.980094] RBP: ffff880117dffcd0 R08: 0000000000000000 R09: 0000000000000000
[   63.980094] R10: 00006c0900006ba8 R11: 00006ba100006b9d R12: 0000000000000001
[   63.980094] R13: ffff8800d02e0898 R14: ffffffff817e6d4d R15: ffff880117387a30
[   63.980094] FS:  0000000000000000(0000) GS:ffff88011a800000(0000) knlGS:0000000000000000
[   63.980094] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   63.980094] CR2: 00007f07e6732fed CR3: 000000011665b000 CR4: 00000000000006e0
[   63.980094] Stack:
[   63.980094]  ffff88011a9cd300 ffffffff82051ac0 ffff880117dffce0 ffffffff817e6d68
[   63.980094]  ffff880117dffd70 ffffffff810cb4c7 ffffffff810cb3cd ffff880117dfffd8
[   63.980094]  ffff880117dea690 ffff880117dea690 ffff880117dfffd8 000000000000000a
[   63.980094] Call Trace:
[   63.980094]  [<ffffffff817e6d68>] u32_delete_key_freepf_rcu+0x1b/0x1d
[   63.980094]  [<ffffffff810cb4c7>] rcu_process_callbacks+0x3bb/0x691
[   63.980094]  [<ffffffff810cb3cd>] ? rcu_process_callbacks+0x2c1/0x691
[   63.980094]  [<ffffffff817e6d4d>] ? u32_destroy_key+0x6d/0x6d
[   63.980094]  [<ffffffff810780a4>] __do_softirq+0x142/0x323
[   63.980094]  [<ffffffff810782a8>] run_ksoftirqd+0x23/0x53
[   63.980094]  [<ffffffff81092126>] smpboot_thread_fn+0x203/0x221
[   63.980094]  [<ffffffff81091f23>] ? smpboot_unpark_thread+0x33/0x33
[   63.980094]  [<ffffffff8108e44d>] kthread+0xc9/0xd1
[   63.980094]  [<ffffffff819e00ea>] ? do_wait_for_common+0xf8/0x125
[   63.980094]  [<ffffffff8108e384>] ? __kthread_parkme+0x61/0x61
[   63.980094]  [<ffffffff819e43ec>] ret_from_fork+0x7c/0xb0
[   63.980094]  [<ffffffff8108e384>] ? __kthread_parkme+0x61/0x61

tp could be freed in call_rcu callback too, the order is not guaranteed.

John Fastabend says:

====================
Its worth noting why this is safe. Any running schedulers will either
read the valid class field or it will be zeroed.

All schedulers today when the class is 0 do a lookup using the
same call used by the tcf_exts_bind(). So even if we have a running
classifier hit the null class pointer it will do a lookup and get
to the same result. This is particularly fragile at the moment because
the only way to verify this is to audit the schedulers call sites.
====================

Cc: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-10-01 22:00:42 -04:00
..
act_api.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
act_csum.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_gact.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_ipt.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_mirred.c net_sched: hold tcf_lock in netdevice notifier 2014-07-20 20:31:42 -07:00
act_nat.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_pedit.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_police.c net: sched: make bstats per cpu and estimator RCU safe 2014-09-30 01:02:26 -04:00
act_simple.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
act_skbedit.c net_sched: act: move tcf_hashinfo_init() into tcf_register_action() 2014-02-12 19:23:32 -05:00
cls_api.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_basic.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_bpf.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_cgroup.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_flow.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_fw.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_route.c net_sched: remove the first parameter from tcf_exts_destroy() 2014-09-28 17:29:01 -04:00
cls_rsvp6.c
cls_rsvp.c
cls_rsvp.h net: sched: cls_rcvp, complete rcu conversion 2014-09-29 00:04:55 -04:00
cls_tcindex.c net_sched: fix another crash in cls_tcindex 2014-10-01 22:00:42 -04:00
cls_u32.c net_sched: avoid calling tcf_unbind_filter() in call_rcu callback 2014-10-01 22:00:42 -04:00
em_canid.c net: em_canid: remove useless statements from em_canid_change 2014-06-21 15:40:22 -07:00
em_cmp.c net_sched: cleanups 2011-01-19 23:31:12 -08:00
em_ipset.c em_ipset: use dev_net() accessor 2013-10-18 16:23:06 -04:00
em_meta.c net: Change skb_get_rxhash to skb_get_hash 2013-12-17 16:36:21 -05:00
em_nbyte.c net_sched: cleanups 2011-01-19 23:31:12 -08:00
em_text.c net_sched: cleanups 2011-01-19 23:31:12 -08:00
em_u32.c net_sched: cleanups 2011-01-19 23:31:12 -08:00
ematch.c net: Convert net_ratelimit uses to net_<level>_ratelimited 2012-05-15 13:45:03 -04:00
Kconfig net: pkt_sched: PIE AQM scheme 2014-01-06 15:13:01 -05:00
Makefile net: pkt_sched: PIE AQM scheme 2014-01-06 15:13:01 -05:00
sch_api.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_atm.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_blackhole.c
sch_cbq.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_choke.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_codel.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_drr.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_dsmark.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_fifo.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_fq_codel.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_fq.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_generic.c net: sched: make bstats per cpu and estimator RCU safe 2014-09-30 01:02:26 -04:00
sch_gred.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_hfsc.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_hhf.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_htb.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_ingress.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_mq.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_mqprio.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_multiq.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_netem.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_pie.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_plug.c net_sched: sch_plug: plug_qdisc_ops is static 2012-02-13 16:04:40 -05:00
sch_prio.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_qfq.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_red.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_sfb.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_sfq.c net: sched: enable per cpu qstats 2014-09-30 01:02:26 -04:00
sch_tbf.c net: sched: implement qstat helper routines 2014-09-30 01:02:26 -04:00
sch_teql.c net: qdisc: use rcu prefix and silence sparse warnings 2014-09-13 12:30:25 -04:00