Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752972AbdCNPFY (ORCPT ); Tue, 14 Mar 2017 11:05:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35574 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752858AbdCNPDM (ORCPT ); Tue, 14 Mar 2017 11:03:12 -0400 Message-ID: <1489503785.2413.10.camel@redhat.com> Subject: Re: net: deadlock between ip_expire/sch_direct_xmit From: Paolo Abeni To: Eric Dumazet , Dmitry Vyukov Cc: David Miller , Eric Dumazet , Cong Wang , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev , LKML , jhs@mojatatu.com, syzkaller Date: Tue, 14 Mar 2017 16:03:05 +0100 In-Reply-To: <1489502504.28631.115.camel@edumazet-glaptop3.roam.corp.google.com> References: <1489502504.28631.115.camel@edumazet-glaptop3.roam.corp.google.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 14 Mar 2017 15:03:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16061 Lines: 329 On Tue, 2017-03-14 at 07:41 -0700, Eric Dumazet wrote: > On Tue, 2017-03-14 at 14:31 +0100, Dmitry Vyukov wrote: > > Hello, > > > > I've got the following deadlock report while running syzkaller fuzzer > > on net-next/92cd12c5ed432c5eebd2462d666772a8d8442c3b: > > > > > > [ INFO: possible circular locking dependency detected ] > > 4.10.0+ #29 Not tainted > > ------------------------------------------------------- > > modprobe/12392 is trying to acquire lock: > > (_xmit_ETHER#2){+.-...}, at: [] spin_lock > > include/linux/spinlock.h:299 [inline] > > (_xmit_ETHER#2){+.-...}, at: [] __netif_tx_lock > > include/linux/netdevice.h:3486 [inline] > > (_xmit_ETHER#2){+.-...}, at: [] > > sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 > > > > but task is already holding lock: > > (&(&q->lock)->rlock){+.-...}, at: [] spin_lock > > include/linux/spinlock.h:299 [inline] > > (&(&q->lock)->rlock){+.-...}, at: [] > > ip_expire+0x51/0x6c0 net/ipv4/ip_fragment.c:201 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (&(&q->lock)->rlock){+.-...}: > > validate_chain kernel/locking/lockdep.c:2267 [inline] > > __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 > > lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 > > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > > _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 > > spin_lock include/linux/spinlock.h:299 [inline] > > ip_defrag+0x3a2/0x4130 net/ipv4/ip_fragment.c:669 > > ip_check_defrag+0x4e3/0x8b0 net/ipv4/ip_fragment.c:713 > > packet_rcv_fanout+0x282/0x800 net/packet/af_packet.c:1459 > > deliver_skb net/core/dev.c:1834 [inline] > > dev_queue_xmit_nit+0x294/0xa90 net/core/dev.c:1890 > > xmit_one net/core/dev.c:2903 [inline] > > dev_hard_start_xmit+0x16b/0xab0 net/core/dev.c:2923 > > sch_direct_xmit+0x31f/0x6d0 net/sched/sch_generic.c:182 > > __dev_xmit_skb net/core/dev.c:3092 [inline] > > __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 > > dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 > > neigh_resolve_output+0x6b9/0xb10 net/core/neighbour.c:1308 > > neigh_output include/net/neighbour.h:478 [inline] > > ip_finish_output2+0x8b8/0x15a0 net/ipv4/ip_output.c:228 > > ip_do_fragment+0x1d93/0x2720 net/ipv4/ip_output.c:672 > > ip_fragment.constprop.54+0x145/0x200 net/ipv4/ip_output.c:545 > > ip_finish_output+0x82d/0xe10 net/ipv4/ip_output.c:314 > > NF_HOOK_COND include/linux/netfilter.h:246 [inline] > > ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 > > dst_output include/net/dst.h:486 [inline] > > ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 > > ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 > > ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 > > raw_sendmsg+0x26de/0x3a00 net/ipv4/raw.c:655 > > inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:761 > > sock_sendmsg_nosec net/socket.c:633 [inline] > > sock_sendmsg+0xca/0x110 net/socket.c:643 > > ___sys_sendmsg+0x4a3/0x9f0 net/socket.c:1985 > > __sys_sendmmsg+0x25c/0x750 net/socket.c:2075 > > SYSC_sendmmsg net/socket.c:2106 [inline] > > SyS_sendmmsg+0x35/0x60 net/socket.c:2101 > > do_syscall_64+0x2e8/0x930 arch/x86/entry/common.c:281 > > return_from_SYSCALL_64+0x0/0x7a > > > > -> #0 (_xmit_ETHER#2){+.-...}: > > check_prev_add kernel/locking/lockdep.c:1830 [inline] > > check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940 > > validate_chain kernel/locking/lockdep.c:2267 [inline] > > __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 > > lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 > > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > > _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 > > spin_lock include/linux/spinlock.h:299 [inline] > > __netif_tx_lock include/linux/netdevice.h:3486 [inline] > > sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 > > __dev_xmit_skb net/core/dev.c:3092 [inline] > > __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 > > dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 > > neigh_hh_output include/net/neighbour.h:468 [inline] > > neigh_output include/net/neighbour.h:476 [inline] > > ip_finish_output2+0xf6c/0x15a0 net/ipv4/ip_output.c:228 > > ip_finish_output+0xa29/0xe10 net/ipv4/ip_output.c:316 > > NF_HOOK_COND include/linux/netfilter.h:246 [inline] > > ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 > > dst_output include/net/dst.h:486 [inline] > > ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 > > ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 > > ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 > > icmp_push_reply+0x372/0x4d0 net/ipv4/icmp.c:394 > > icmp_send+0x156c/0x1c80 net/ipv4/icmp.c:754 > > ip_expire+0x40e/0x6c0 net/ipv4/ip_fragment.c:239 > > call_timer_fn+0x241/0x820 kernel/time/timer.c:1268 > > expire_timers kernel/time/timer.c:1307 [inline] > > __run_timers+0x960/0xcf0 kernel/time/timer.c:1601 > > run_timer_softirq+0x21/0x80 kernel/time/timer.c:1614 > > __do_softirq+0x31f/0xbe7 kernel/softirq.c:284 > > invoke_softirq kernel/softirq.c:364 [inline] > > irq_exit+0x1cc/0x200 kernel/softirq.c:405 > > exiting_irq arch/x86/include/asm/apic.h:657 [inline] > > smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:962 > > apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:707 > > __read_once_size include/linux/compiler.h:254 [inline] > > atomic_read arch/x86/include/asm/atomic.h:26 [inline] > > rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:350 [inline] > > __rcu_is_watching kernel/rcu/tree.c:1133 [inline] > > rcu_is_watching+0x83/0x110 kernel/rcu/tree.c:1147 > > rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:293 > > radix_tree_deref_slot include/linux/radix-tree.h:238 [inline] > > filemap_map_pages+0x6d4/0x1570 mm/filemap.c:2335 > > do_fault_around mm/memory.c:3231 [inline] > > do_read_fault mm/memory.c:3265 [inline] > > do_fault+0xbd5/0x2080 mm/memory.c:3370 > > handle_pte_fault mm/memory.c:3600 [inline] > > __handle_mm_fault+0x1062/0x2cb0 mm/memory.c:3714 > > handle_mm_fault+0x1e2/0x480 mm/memory.c:3751 > > __do_page_fault+0x4f6/0xb60 arch/x86/mm/fault.c:1397 > > do_page_fault+0x54/0x70 arch/x86/mm/fault.c:1460 > > page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1011 > > > > other info that might help us debug this: > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&(&q->lock)->rlock); > > lock(_xmit_ETHER#2); > > lock(&(&q->lock)->rlock); > > lock(_xmit_ETHER#2); > > > > *** DEADLOCK *** > > > > 10 locks held by modprobe/12392: > > #0: (&mm->mmap_sem){++++++}, at: [] > > __do_page_fault+0x2b8/0xb60 arch/x86/mm/fault.c:1336 > > #1: (rcu_read_lock){......}, at: [] > > filemap_map_pages+0x1e6/0x1570 mm/filemap.c:2324 > > #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] > > spin_lock include/linux/spinlock.h:299 [inline] > > #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] > > pte_alloc_one_map mm/memory.c:2944 [inline] > > #2: (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [] > > alloc_set_pte+0x13b8/0x1b90 mm/memory.c:3072 > > #3: (((&q->timer))){+.-...}, at: [] > > lockdep_copy_map include/linux/lockdep.h:175 [inline] > > #3: (((&q->timer))){+.-...}, at: [] > > call_timer_fn+0x1c2/0x820 kernel/time/timer.c:1258 > > #4: (&(&q->lock)->rlock){+.-...}, at: [] spin_lock > > include/linux/spinlock.h:299 [inline] > > #4: (&(&q->lock)->rlock){+.-...}, at: [] > > ip_expire+0x51/0x6c0 net/ipv4/ip_fragment.c:201 > > #5: (rcu_read_lock){......}, at: [] > > ip_expire+0x1b3/0x6c0 net/ipv4/ip_fragment.c:216 > > #6: (slock-AF_INET){+.-...}, at: [] spin_trylock > > include/linux/spinlock.h:309 [inline] > > #6: (slock-AF_INET){+.-...}, at: [] icmp_xmit_lock > > net/ipv4/icmp.c:219 [inline] > > #6: (slock-AF_INET){+.-...}, at: [] > > icmp_send+0x803/0x1c80 net/ipv4/icmp.c:681 > > #7: (rcu_read_lock_bh){......}, at: [] > > ip_finish_output2+0x2c1/0x15a0 net/ipv4/ip_output.c:198 > > #8: (rcu_read_lock_bh){......}, at: [] > > __dev_queue_xmit+0x23e/0x1e60 net/core/dev.c:3324 > > #9: (dev->qdisc_running_key ?: &qdisc_running_key){+.....}, at: > > [] dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 > > > > stack backtrace: > > CPU: 0 PID: 12392 Comm: modprobe Not tainted 4.10.0+ #29 > > Hardware name: Google Google Compute Engine/Google Compute Engine, > > BIOS Google 01/01/2011 > > Call Trace: > > > > __dump_stack lib/dump_stack.c:16 [inline] > > dump_stack+0x2ee/0x3ef lib/dump_stack.c:52 > > print_circular_bug+0x307/0x3b0 kernel/locking/lockdep.c:1204 > > check_prev_add kernel/locking/lockdep.c:1830 [inline] > > check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940 > > validate_chain kernel/locking/lockdep.c:2267 [inline] > > __lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340 > > lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 > > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > > _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151 > > spin_lock include/linux/spinlock.h:299 [inline] > > __netif_tx_lock include/linux/netdevice.h:3486 [inline] > > sch_direct_xmit+0x282/0x6d0 net/sched/sch_generic.c:180 > > __dev_xmit_skb net/core/dev.c:3092 [inline] > > __dev_queue_xmit+0x13e5/0x1e60 net/core/dev.c:3358 > > dev_queue_xmit+0x17/0x20 net/core/dev.c:3423 > > neigh_hh_output include/net/neighbour.h:468 [inline] > > neigh_output include/net/neighbour.h:476 [inline] > > ip_finish_output2+0xf6c/0x15a0 net/ipv4/ip_output.c:228 > > ip_finish_output+0xa29/0xe10 net/ipv4/ip_output.c:316 > > NF_HOOK_COND include/linux/netfilter.h:246 [inline] > > ip_output+0x1f0/0x7a0 net/ipv4/ip_output.c:404 > > dst_output include/net/dst.h:486 [inline] > > ip_local_out+0x95/0x170 net/ipv4/ip_output.c:124 > > ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1492 > > ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1512 > > icmp_push_reply+0x372/0x4d0 net/ipv4/icmp.c:394 > > icmp_send+0x156c/0x1c80 net/ipv4/icmp.c:754 > > ip_expire+0x40e/0x6c0 net/ipv4/ip_fragment.c:239 > > call_timer_fn+0x241/0x820 kernel/time/timer.c:1268 > > expire_timers kernel/time/timer.c:1307 [inline] > > __run_timers+0x960/0xcf0 kernel/time/timer.c:1601 > > run_timer_softirq+0x21/0x80 kernel/time/timer.c:1614 > > __do_softirq+0x31f/0xbe7 kernel/softirq.c:284 > > invoke_softirq kernel/softirq.c:364 [inline] > > irq_exit+0x1cc/0x200 kernel/softirq.c:405 > > exiting_irq arch/x86/include/asm/apic.h:657 [inline] > > smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:962 > > apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:707 > > RIP: 0010:__read_once_size include/linux/compiler.h:254 [inline] > > RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline] > > RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:350 [inline] > > RIP: 0010:__rcu_is_watching kernel/rcu/tree.c:1133 [inline] > > RIP: 0010:rcu_is_watching+0x83/0x110 kernel/rcu/tree.c:1147 > > RSP: 0000:ffff8801c391f120 EFLAGS: 00000a03 ORIG_RAX: ffffffffffffff10 > > RAX: dffffc0000000000 RBX: ffff8801c391f148 RCX: 0000000000000000 > > RDX: 0000000000000000 RSI: 000055edd4374000 RDI: ffff8801dbe1ae0c > > RBP: ffff8801c391f1a0 R08: 0000000000000002 R09: 0000000000000000 > > R10: dffffc0000000000 R11: 0000000000000002 R12: 1ffff10038723e25 > > R13: ffff8801dbe1ae00 R14: ffff8801c391f680 R15: dffffc0000000000 > > > > rcu_read_lock_held+0x87/0xc0 kernel/rcu/update.c:293 > > radix_tree_deref_slot include/linux/radix-tree.h:238 [inline] > > filemap_map_pages+0x6d4/0x1570 mm/filemap.c:2335 > > do_fault_around mm/memory.c:3231 [inline] > > do_read_fault mm/memory.c:3265 [inline] > > do_fault+0xbd5/0x2080 mm/memory.c:3370 > > handle_pte_fault mm/memory.c:3600 [inline] > > __handle_mm_fault+0x1062/0x2cb0 mm/memory.c:3714 > > handle_mm_fault+0x1e2/0x480 mm/memory.c:3751 > > __do_page_fault+0x4f6/0xb60 arch/x86/mm/fault.c:1397 > > do_page_fault+0x54/0x70 arch/x86/mm/fault.c:1460 > > page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1011 > > RIP: 0033:0x7f83172f2786 > > RSP: 002b:00007fffe859ae80 EFLAGS: 00010293 > > RAX: 000055edd4373040 RBX: 00007f83175111c8 RCX: 000055edd4373238 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f8317510970 > > RBP: 00007fffe859afd0 R08: 0000000000000009 R09: 0000000000000000 > > R10: 0000000000000064 R11: 0000000000000000 R12: 000055edd4373040 > > R13: 0000000000000000 R14: 00007fffe859afe8 R15: 0000000000000000 > > > This looks a false positive. > An ICMP message can not be possibly fragmented. > Following patch should fix the lockdep issue. > > diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c > index bbe7f72db9c157ba2d6c5292637c2f58ad39a123..b3cdeec85f1f2c612c362590e828f50596a5c247 100644 > --- a/net/ipv4/ip_fragment.c > +++ b/net/ipv4/ip_fragment.c > @@ -198,6 +198,7 @@ static void ip_expire(unsigned long arg) > qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); > net = container_of(qp->q.net, struct net, ipv4.frags); > > + rcu_read_lock(); > spin_lock(&qp->q.lock); > > if (qp->q.flags & INET_FRAG_COMPLETE) > @@ -207,7 +208,7 @@ static void ip_expire(unsigned long arg) > __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); > > if (!inet_frag_evicting(&qp->q)) { > - struct sk_buff *head = qp->q.fragments; > + struct sk_buff *clone, *head = qp->q.fragments; > const struct iphdr *iph; > int err; > > @@ -216,32 +217,40 @@ static void ip_expire(unsigned long arg) > if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !qp->q.fragments) > goto out; > > - rcu_read_lock(); > head->dev = dev_get_by_index_rcu(net, qp->iif); > if (!head->dev) > - goto out_rcu_unlock; > + goto out; > + > > /* skb has no dst, perform route lookup again */ > iph = ip_hdr(head); > err = ip_route_input_noref(head, iph->daddr, iph->saddr, > iph->tos, head->dev); > if (err) > - goto out_rcu_unlock; > + goto out; > > /* Only an end host needs to send an ICMP > * "Fragment Reassembly Timeout" message, per RFC792. > */ > if (frag_expire_skip_icmp(qp->user) && > (skb_rtable(head)->rt_type != RTN_LOCAL)) > - goto out_rcu_unlock; > + goto out; > + > + clone = skb_clone(head, GFP_ATOMIC); > > /* Send an ICMP "Fragment Reassembly Timeout" message. */ > - icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); > -out_rcu_unlock: > - rcu_read_unlock(); > + if (clone) { > + spin_unlock(&qp->q.lock); > + icmp_send(clone, ICMP_TIME_EXCEEDED, > + ICMP_EXC_FRAGTIME, 0); > + consume_skb(clone); > + goto out_rcu_unlock; > + } > } > out: > spin_unlock(&qp->q.lock); I'm wondering if we really need to keep the fragment queue lock held while sending the icmp packet ? we hold a reference to the struct, so it can't be deleted, and AFAICS after ipq_kill() nobody else could access/modify that queue. That lock is there pretty much forever, but perhaps is only a leftover and we can release it just after ipq_kill() ? Paolo