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| author |   WANG Cong <xiyou.wangcong@gmail.com> | 2014-09-30 16:07:24 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2014-10-01 22:00:42 -0400 |
| commit | a0efb80ce3abacfd22a4284c3730924fc2f1f077 (patch) | |
| tree | b611eb85ef732f3d9d09f5ca0759c30d185278a7 /net | |
| parent | net_sched: fix another crash in cls_tcindex (diff) | |
| download | linux-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 'net')
| -rw-r--r-- | net/sched/cls_u32.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 4be3ebf46d67..0472909bb014 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -358,7 +358,6 @@ static int u32_destroy_key(struct tcf_proto *tp, struct tc_u_knode *n, bool free_pf) { - tcf_unbind_filter(tp, &n->res); tcf_exts_destroy(&n->exts); if (n->ht_down) n->ht_down->refcnt--; @@ -416,6 +415,7 @@ static int u32_delete_key(struct tcf_proto *tp, struct tc_u_knode *key) if (pkp == key) { RCU_INIT_POINTER(*kp, key->next); + tcf_unbind_filter(tp, &key->res); call_rcu(&key->rcu, u32_delete_key_freepf_rcu); return 0; } @@ -425,7 +425,7 @@ static int u32_delete_key(struct tcf_proto *tp, struct tc_u_knode *key) return 0; } -static void u32_clear_hnode(struct tc_u_hnode *ht) +static void u32_clear_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht) { struct tc_u_knode *n; unsigned int h; @@ -434,6 +434,7 @@ static void u32_clear_hnode(struct tc_u_hnode *ht) while ((n = rtnl_dereference(ht->ht[h])) != NULL) { RCU_INIT_POINTER(ht->ht[h], rtnl_dereference(n->next)); + tcf_unbind_filter(tp, &n->res); call_rcu(&n->rcu, u32_delete_key_freepf_rcu); } } @@ -447,7 +448,7 @@ static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht) WARN_ON(ht->refcnt); - u32_clear_hnode(ht); + u32_clear_hnode(tp, ht); hn = &tp_c->hlist; for (phn = rtnl_dereference(*hn); @@ -482,7 +483,7 @@ static void u32_destroy(struct tcf_proto *tp) ht; ht = rtnl_dereference(ht->next)) { ht->refcnt--; - u32_clear_hnode(ht); + u32_clear_hnode(tp, ht); } while ((ht = rtnl_dereference(tp_c->hlist)) != NULL) { @@ -731,6 +732,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, } u32_replace_knode(tp, tp_c, new); + tcf_unbind_filter(tp, &n->res); call_rcu(&n->rcu, u32_delete_key_rcu); return 0; } |