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Eric Dumazet cf657d22ee net/x25: do not hold the cpu too long in x25_new_lci() 
Due to quadratic behavior of x25_new_lci(), syzbot was able
to trigger an rcu stall.

Fix this by not blocking BH for the whole duration of
the function, and inserting a reschedule point when possible.

If we care enough, using a bitmap could get rid of the quadratic
behavior.

syzbot report :

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu:    0-...!: (10500 ticks this GP) idle=4fa/1/0x4000000000000002 softirq=283376/283376 fqs=0
rcu:     (t=10501 jiffies g=383105 q=136)
rcu: rcu_preempt kthread starved for 10502 jiffies! g383105 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I28928    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2844 [inline]
 __schedule+0x817/0x1cc0 kernel/sched/core.c:3485
 schedule+0x92/0x180 kernel/sched/core.c:3529
 schedule_timeout+0x4db/0xfd0 kernel/time/timer.c:1803
 rcu_gp_fqs_loop kernel/rcu/tree.c:1948 [inline]
 rcu_gp_kthread+0x956/0x17a0 kernel/rcu/tree.c:2105
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 8759 Comm: syz-executor2 Not tainted 5.0.0-rc4+ #51
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1be/0x236 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x183/0x1cf kernel/rcu/tree.c:1211
 print_cpu_stall kernel/rcu/tree.c:1348 [inline]
 check_cpu_stall kernel/rcu/tree.c:1422 [inline]
 rcu_pending kernel/rcu/tree.c:3018 [inline]
 rcu_check_callbacks.cold+0x500/0xa4a kernel/rcu/tree.c:2521
 update_process_times+0x32/0x80 kernel/time/timer.c:1635
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:161
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1271
 __run_hrtimer kernel/time/hrtimer.c:1389 [inline]
 __hrtimer_run_queues+0x33e/0xde0 kernel/time/hrtimer.c:1451
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1035 [inline]
 smp_apic_timer_interrupt+0x120/0x570 arch/x86/kernel/apic/apic.c:1060
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:193 [inline]
RIP: 0010:queued_write_lock_slowpath+0x13e/0x290 kernel/locking/qrwlock.c:86
Code: 00 00 fc ff df 4c 8d 2c 01 41 83 c7 03 41 0f b6 45 00 41 38 c7 7c 08 84 c0 0f 85 0c 01 00 00 8b 03 3d 00 01 00 00 74 1a f3 90 <41> 0f b6 55 00 41 38 d7 7c eb 84 d2 74 e7 48 89 df e8 6c 0f 4f 00
RSP: 0018:ffff88805f117bd8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000300 RBX: ffffffff89413ba0 RCX: 1ffffffff1282774
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff89413ba0
RBP: ffff88805f117c70 R08: 1ffffffff1282774 R09: fffffbfff1282775
R10: fffffbfff1282774 R11: ffffffff89413ba3 R12: 00000000000000ff
R13: fffffbfff1282774 R14: 1ffff1100be22f7d R15: 0000000000000003
 queued_write_lock include/asm-generic/qrwlock.h:104 [inline]
 do_raw_write_lock+0x1d6/0x290 kernel/locking/spinlock_debug.c:203
 __raw_write_lock_bh include/linux/rwlock_api_smp.h:204 [inline]
 _raw_write_lock_bh+0x3b/0x50 kernel/locking/spinlock.c:312
 x25_insert_socket+0x21/0xe0 net/x25/af_x25.c:267
 x25_bind+0x273/0x340 net/x25/af_x25.c:705
 __sys_bind+0x23f/0x290 net/socket.c:1505
 __do_sys_bind net/socket.c:1516 [inline]
 __se_sys_bind net/socket.c:1514 [inline]
 __x64_sys_bind+0x73/0xb0 net/socket.c:1514
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e39
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fafccd0dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e39
RDX: 0000000000000012 RSI: 0000000020000240 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fafccd0e6d4
R13: 00000000004bdf8b R14: 00000000004ce4b8 R15: 00000000ffffffff
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8752 Comm: syz-executor4 Not tainted 5.0.0-rc4+ #51
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__x25_find_socket+0x78/0x120 net/x25/af_x25.c:328
Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 a6 00 00 00 4d 8b 64 24 68 4d 85 e4 74 7f e8 03 97 3d fb 49 83 ec 68 74 74 e8 f8 96 3d fb <49> 8d bc 24 88 04 00 00 48 89 f8 48 c1 e8 03 0f b6 04 18 84 c0 74
RSP: 0018:ffff8880639efc58 EFLAGS: 00000246
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc9000e677000
RDX: 0000000000040000 RSI: ffffffff863244b8 RDI: ffff88806a764628
RBP: ffff8880639efc80 R08: ffff8880a80d05c0 R09: fffffbfff1282775
R10: fffffbfff1282774 R11: ffffffff89413ba3 R12: ffff88806a7645c0
R13: 0000000000000001 R14: ffff88809f29ac00 R15: 0000000000000000
FS:  00007fe8d0c58700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32823000 CR3: 00000000672eb000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 x25_new_lci net/x25/af_x25.c:357 [inline]
 x25_connect+0x374/0xdf0 net/x25/af_x25.c:786
 __sys_connect+0x266/0x330 net/socket.c:1686
 __do_sys_connect net/socket.c:1697 [inline]
 __se_sys_connect net/socket.c:1694 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1694
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e39
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe8d0c57c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e39
RDX: 0000000000000012 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe8d0c586d4
R13: 00000000004be378 R14: 00000000004ceb00 R15: 00000000ffffffff

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Cc: linux-x25@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-02-11 13:20:14 -08:00
..
6lowpan 6lowpan: convert to DEFINE_SHOW_ATTRIBUTE 2018-12-19 00:28:05 +01:00
9p 9p/net: put a lower bound on msize 2018-12-25 17:07:49 +09:00
802
8021q net: core: dev: Add extack argument to dev_change_flags() 2018-12-06 13:26:07 -08:00
appletalk
atm Revert "net: simplify sock_poll_wait" 2018-10-23 10:57:06 -07:00
ax25 ax25: fix possible use-after-free 2019-01-23 11:18:00 -08:00
batman-adv Here are some batman-adv bugfixes: 2019-02-01 10:19:26 -08:00
bluetooth Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-12-27 13:53:32 -08:00
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-12-10 18:00:43 -08:00
bpfilter net: bpfilter: change section name of bpfilter UMH blob. 2019-01-16 15:46:46 -08:00
bridge Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2019-01-28 10:51:51 -08:00
caif Revert "net: simplify sock_poll_wait" 2018-10-23 10:57:06 -07:00
can can: bcm: check timer values before ktime conversion 2019-01-22 11:33:46 +01:00
ceph libceph: avoid KEEPALIVE_PENDING races in ceph_con_keepalive() 2019-01-21 14:53:12 +01:00
core Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2019-02-01 15:28:07 -08:00
dcb
dccp dccp: fool proof ccid_hc_[rt]x_parse_options() 2019-02-01 14:49:10 -08:00
decnet decnet: fix DN_IFREQ_SIZE 2019-01-27 23:11:55 -08:00
dns_resolver dns: Allow the dns resolver to retrieve a server set 2018-10-04 09:40:52 -07:00
dsa net: dsa: Fix NULL checking in dsa_slave_set_eee() 2019-02-06 13:42:54 -08:00
ethernet net: ethernet: provide nvmem_get_mac_address() 2018-12-03 15:40:30 -08:00
hsr
ieee802154 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-24 16:19:56 -08:00
ife
ipv4 netfilter: nat: fix spurious connection timeouts 2019-02-11 17:43:17 +01:00
ipv6 netfilter: nat: fix spurious connection timeouts 2019-02-11 17:43:17 +01:00
iucv iucv: Remove SKB list assumptions. 2018-11-10 16:55:11 -08:00
kcm
key af_key: fix indentation on declaration statement 2018-11-15 18:09:32 +01:00
l2tp l2tp: copy 4 more bytes to linear part if necessary 2019-01-31 08:58:46 -08:00
l3mdev l3mdev: add function to retreive upper master 2018-12-03 14:15:26 -08:00
lapb
llc llc: do not use sk_eat_skb() 2018-10-22 19:59:20 -07:00
mac80211 mac80211: ensure that mgmt tx skbs have tailroom for encryption 2019-02-01 11:08:02 +01:00
mac802154
mpls net/mpls: Handle kernel side filtering of route dumps 2018-10-16 00:14:07 -07:00
ncsi net/ncsi: Add NCSI Mellanox OEM command 2018-11-27 16:37:20 -08:00
netfilter netfilter: nft_compat: don't use refcount_inc on newly allocated entry 2019-02-05 14:10:33 +01:00
netlabel
netlink net: netlink: rename NETLINK_DUMP_STRICT_CHK -> NETLINK_GET_STRICT_CHK 2018-12-14 11:44:31 -08:00
netrom netrom: switch to sock timer API 2019-01-27 10:38:04 -08:00
nfc net: Revert recent Spectre-v1 patches. 2018-12-23 16:01:35 -08:00
nsh
openvswitch openvswitch: Avoid OOB read when parsing flow nlattrs 2019-01-16 13:35:21 -08:00
packet af_packet: fix raw sockets over 6in4 tunnel 2019-01-17 15:54:45 -08:00
phonet net: Revert recent Spectre-v1 patches. 2018-12-23 16:01:35 -08:00
psample
qrtr
rds rds: fix refcount bug in rds_sock_addref 2019-01-31 09:43:27 -08:00
rfkill rfkill: gpio: Remove unused include 2018-12-18 13:13:56 +01:00
rose net/rose: fix NULL ax25_cb kernel panic 2019-01-27 10:40:01 -08:00
rxrpc rxrpc: bad unlock balance in rxrpc_recvmsg 2019-02-06 10:54:07 -08:00
sched Documentation: bring operstate documentation up-to-date 2019-02-11 12:38:51 -08:00
sctp sctp: check and update stream->out_curr when allocating stream_out 2019-02-03 14:27:47 -08:00
smc net/smc: fix byte_order for rx_curs_confirmed 2019-02-08 22:33:25 -08:00
strparser bpf, sockmap: convert to generic sk_msg interface 2018-10-15 12:23:19 -07:00
sunrpc svcrdma: Remove max_sge check at connect time 2019-02-06 15:32:34 -05:00
switchdev net: switchdev: Add extack to switchdev_handle_port_obj_add() callback 2018-12-12 16:34:22 -08:00
tipc tipc: fix uninit-value in tipc_nl_compat_doit 2019-01-15 20:29:21 -08:00
tls net: tls: Fix deadlock in free_resources tx 2019-01-28 23:07:08 -08:00
unix Revert "net: simplify sock_poll_wait" 2018-10-23 10:57:06 -07:00
vmw_vsock vsock: cope with memory allocation failure at socket creation time 2019-02-08 22:32:05 -08:00
wimax
wireless cfg80211: call disconnect_wk when AP stops 2019-02-01 11:12:50 +01:00
x25 net/x25: do not hold the cpu too long in x25_new_lci() 2019-02-11 13:20:14 -08:00
xdp xsk: Check if a queue exists during umem setup 2019-01-15 20:51:57 +01:00
xfrm xfrm: Make set-mark default behavior backward compatible 2019-01-16 13:10:55 +01:00
compat.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
Kconfig net: convert bridge_nf to use skb extension infrastructure 2018-12-19 11:21:37 -08:00
Makefile
socket.c net: socket: make bond ioctls go through compat_ifreq_ioctl() 2019-01-30 10:19:31 -08:00
sysctl_net.c