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authorWANG Cong <xiyou.wangcong@gmail.com>2014-09-30 16:07:24 -0700
committerDavid S. Miller <davem@davemloft.net>2014-10-01 22:00:42 -0400
commita0efb80ce3abacfd22a4284c3730924fc2f1f077 (patch)
treeb611eb85ef732f3d9d09f5ca0759c30d185278a7 /net/bridge/br_stp_if.c
parentnet_sched: fix another crash in cls_tcindex (diff)
downloadlinux-dev-a0efb80ce3abacfd22a4284c3730924fc2f1f077.tar.xz
linux-dev-a0efb80ce3abacfd22a4284c3730924fc2f1f077.zip
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>
Diffstat (limited to '')
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