Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751887AbdCNOm5 (ORCPT ); Tue, 14 Mar 2017 10:42:57 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:34416 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750919AbdCNOlr (ORCPT ); Tue, 14 Mar 2017 10:41:47 -0400 Message-ID: <1489502504.28631.115.camel@edumazet-glaptop3.roam.corp.google.com> Subject: Re: net: deadlock between ip_expire/sch_direct_xmit From: Eric Dumazet To: 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 07:41:44 -0700 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 15073 Lines: 326 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); +out_rcu_unlock: + rcu_read_unlock(); ipq_put(qp); }