syzbot

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3c66/0x5270 kernel/locking/lockdep.c:3092
Read of size 8 at addr ffff8801c7524d20 by task syz-executor504/13817

CPU: 0 PID: 13817 Comm: syz-executor504 Not tainted 4.4.141-gb1bad9e #69
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 c7670726adf43894 ffff8800b1b47a70 ffffffff81e0e16d
 ffffea00071d4800 ffff8801c7524d20 0000000000000000 ffff8801c7524d20
 0000000000000000 ffff8800b1b47aa8 ffffffff81515a76 ffff8801c7524d20
Call Trace:
 [<ffffffff81e0e16d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0e16d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81515a76>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515d95>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515d95>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9884>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff81232cc6>] __lock_acquire+0x3c66/0x5270 kernel/locking/lockdep.c:3092
 [<ffffffff81235aae>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff838c1d9a>] __raw_spin_lock_bh include/linux/spinlock_api_smp.h:137 [inline]
 [<ffffffff838c1d9a>] _raw_spin_lock_bh+0x3a/0x50 kernel/locking/spinlock.c:175
 [<ffffffff82f26973>] spin_lock_bh include/linux/spinlock.h:307 [inline]
 [<ffffffff82f26973>] lock_sock_nested+0x43/0x120 net/core/sock.c:2451
 [<ffffffff835a7ac0>] lock_sock include/net/sock.h:1493 [inline]
 [<ffffffff835a7ac0>] pppol2tp_release+0x50/0x310 net/l2tp/l2tp_ppp.c:493
 [<ffffffff82f1a166>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a2a6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522e65>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff815233a5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bdaf>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:349
 [<ffffffff838c2cb5>] int_ret_from_sys_call+0x25/0xa3

Allocated by task 13819:
 [<ffffffff81033c86>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8933>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8c17>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8c17>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f5334>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff82f25834>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff82f25834>] sk_prot_alloc+0x204/0x300 net/core/sock.c:1354
 [<ffffffff82f2b20a>] sk_alloc+0x3a/0x3a0 net/core/sock.c:1419
 [<ffffffff835a39e3>] pppol2tp_create+0x33/0x1f0 net/l2tp/l2tp_ppp.c:551
 [<ffffffff828f1ad6>] pppox_create+0xf6/0x200 drivers/net/ppp/pppox.c:121
 [<ffffffff82f20690>] __sock_create+0x2f0/0x5f0 net/socket.c:1177
 [<ffffffff82f20bc0>] sock_create net/socket.c:1217 [inline]
 [<ffffffff82f20bc0>] SYSC_socket net/socket.c:1247 [inline]
 [<ffffffff82f20bc0>] SyS_socket+0xf0/0x1b0 net/socket.c:1227
 [<ffffffff838c2b25>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 13817:
 [<ffffffff81033c86>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8933>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f9262>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f9262>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f6764>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f6764>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f6764>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f6764>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff82f2f6b7>] sk_prot_free net/core/sock.c:1391 [inline]
 [<ffffffff82f2f6b7>] sk_destruct+0x407/0x4c0 net/core/sock.c:1472
 [<ffffffff82f2f7bf>] __sk_free+0x4f/0x220 net/core/sock.c:1480
 [<ffffffff82f2f9c0>] sk_free+0x30/0x40 net/core/sock.c:1491
 [<ffffffff835a6f9f>] sock_put include/net/sock.h:1639 [inline]
 [<ffffffff835a6f9f>] pppol2tp_session_sock_put+0x5f/0x70 net/l2tp/l2tp_ppp.c:286
 [<ffffffff8359f81c>] l2tp_tunnel_closeall+0x23c/0x350 net/l2tp/l2tp_core.c:1277
 [<ffffffff835a03ab>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff834926d1>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421
 [<ffffffff82f2fa3d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff83491385>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f8e3f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff8341bab0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82f1a166>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a2a6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522e65>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff815233a5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bdaf>] task_work_run+0x10f/0x190 kernel/task_work.c:115
 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:349
 [<ffffffff838c2cb5>] int_ret_from_sys_call+0x25/0xa3

The buggy address belongs to the object at ffff8801c7524c80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff8801c7524c80, ffff8801c7525480)
The buggy address belongs to the page:
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Initializing cgroup subsys schedtune
Linux version 4.4.141-gb1bad9e (syzkaller@ci) (gcc version 8.0.1 20180413 (experimental) (GCC) ) #69 SMP PREEMPT Tue Jul 17 10:56:53 UTC 2018
Command line: BOOT_IMAGE=/vmlinuz root=/dev/sda1 console=ttyS0 earlyprintk=serial vsyscall=native rodata=n ftrace_dump_on_oops=orig_cpu oops=panic panic_on_warn=1 nmi_watchdog=panic panic=86400 workqueue.watchdog_thresh=140 nopti
KERNEL supported cpus:
  Intel GenuineIntel
  AMD AuthenticAMD
  Centaur CentaurHauls
x86/fpu: xstate_offset[2]:  576, xstate_sizes[2]:  256
x86/fpu: Supporting XSAVE feature 0x01: 'x87 floating point registers'
x86/fpu: Supporting XSAVE feature 0x02: 'SSE registers'
x86/fpu: Supporting XSAVE feature 0x04: 'AVX registers'
x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format.
e820: BIOS-provided physical RAM map:
BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
BIOS-e820: [mem 0x0000000000100000-0x00000000bfff2fff] usable
BIOS-e820: [mem 0x00000000bfff3000-0x00000000bfffffff] reserved
BIOS-e820: [mem 0x00000000fffbc000-0x00000000ffffffff] reserved
BIOS-e820: [mem 0x0000000100000000-0x000000021fffffff] usable
bootconsole [earlyser0] enabled
NX (Execute Disable) protection: active
SMBIOS 2.4 present.
Hypervisor detected: KVM
Kernel/User page tables isolation: disabled
e820: last_pfn = 0x220000 max_arch_pfn = 0x400000000
x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- WT  
e820: last_pfn = 0xbfff3 max_arch_pfn = 0x400000000
found SMP MP-table at [mem 0x000f2310-0x000f231f] mapped at [ffff8800000f2310]
Scanning 1 areas for low memory corruption
Using GB pages for direct mapping
ACPI: Early table checksum verification disabled
ACPI: RSDP 0x00000000000F22D0 000014 (v00 Google)
ACPI: RSDT 0x00000000BFFF3430 000038 (v01 Google GOOGRSDT 00000001 GOOG 00000001)
ACPI: FACP 0x00000000BFFFCF60 0000F4 (v02 Google GOOGFACP 00000001 GOOG 00000001)
ACPI: DSDT 0x00000000BFFF3470 0017B2 (v01 Google GOOGDSDT 00000001 GOOG 00000001)
ACPI: FACS 0x00000000BFFFCF00 000040
ACPI: FACS 0x00000000BFFFCF00 000040
ACPI: SSDT 0x00000000BFFF65F0 00690D (v01 Google GOOGSSDT 00000001 GOOG 00000001)
ACPI: APIC 0x00000000BFFF5D10 000076 (v01 Google GOOGAPIC 00000001 GOOG 00000001)
ACPI: WAET 0x00000000BFFF5CE0 000028 (v01 Google GOOGWAET 00000001 GOOG 00000001)
ACPI: SRAT 0x00000000BFFF4C30 0000C8 (v01 Google GOOGSRAT 00000001 GOOG 00000001)
kvm-clock: Using msrs 4b564d01 and 4b564d00
kvm-clock: cpu 0, msr 2:1fffd001, primary cpu clock
kvm-clock: using sched offset of 2552094318 cycles
clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
Zone ranges:
  DMA      [mem 0x0000000000001000-0x0000000000ffffff]
  DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
  Normal   [mem 0x0000000100000000-0x000000021fffffff]
Movable zone start for each node
Early memory node ranges
  node   0: [mem 0x0000000000001000-0x000000000009efff]
  node   0: [mem 0x0000000000100000-0x00000000bfff2fff]
  node   0: [mem 0x0000000100000000-0x000000021fffffff]
Initmem setup node 0 [mem 0x0000000000001000-0x000000021fffffff]
kasan: KernelAddressSanitizer initialized
ACPI: PM-Timer IO Port: 0xb008
ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
ACPI: INT_SRC_OVR (bus 0 bus_irq 5 global_irq 5 high level)
ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
ACPI: INT_SRC_OVR (bus 0 bus_irq 10 global_irq 10 high level)
ACPI: INT_SRC_OVR (bus 0 bus_irq 11 global_irq 11 high level)
Using ACPI (MADT) for SMP configuration information
smpboot: Allowing 2 CPUs, 0 hotplug CPUs
PM: Registered nosave memory: [mem 0x00000000-0x00000fff]
PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
PM: Registered nosave memory: [mem 0x000a0000-0x000effff]
PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
PM: Registered nosave memory: [mem 0xbfff3000-0xbfffffff]
PM: Registered nosave memory: [mem 0xc0000000-0xfffbbfff]
PM: Registered nosave memory: [mem 0xfffbc000-0xffffffff]
e820: [mem 0xc0000000-0xfffbbfff] available for PCI devices
Booting paravirtualized kernel on KVM
clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
setup_percpu: NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:2 nr_node_ids:1
PERCPU: Embedded 42 pages/cpu @ffff8801db200000 s134024 r8192 d29816 u1048576
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 1935227
Kernel command line: BOOT_IMAGE=/vmlinuz root=/dev/sda1 console=ttyS0 earlyprintk=serial vsyscall=native rodata=n ftrace_dump_on_oops=orig_cpu oops=panic panic_on_warn=1 nmi_watchdog=panic panic=86400 workqueue.watchdog_thresh=140 nopti
PID hash table entries: 4096 (order: 3, 32768 bytes)
Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes)
Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes)
Memory: 6579092K/7863876K available (41762K kernel code, 6303K rwdata, 9052K rodata, 1864K init, 23696K bss, 1284784K reserved, 0K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
Running RCU self tests
Preemptible hierarchical RCU implementation.
	RCU lockdep checking is enabled.
	Build-time adjustment of leaf fanout to 64.
	RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=2.
RCU: Adjusting geometry for rcu_fanout_leaf=64, nr_cpu_ids=2
NR_IRQS:4352 nr_irqs:440 16
console [ttyS0] enabled
console [ttyS0] enabled
bootconsole [earlyser0] disabled
bootconsole [earlyser0] disabled
Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
... MAX_LOCKDEP_SUBCLASSES:  8
... MAX_LOCK_DEPTH:          48
... MAX_LOCKDEP_KEYS:        8191
... CLASSHASH_SIZE:          4096
... MAX_LOCKDEP_ENTRIES:     32768
... MAX_LOCKDEP_CHAINS:      65536
... CHAINHASH_SIZE:          32768
 memory used by lock dependency info: 8159 kB
 per task-struct memory footprint: 1920 bytes
tsc: Detected 2300.000 MHz processor
Calibrating delay loop (skipped) preset value.. 4600.00 BogoMIPS (lpj=23000000)
pid_max: default: 32768 minimum: 301
ACPI: Core revision 20150930
ACPI: 2 ACPI AML tables successfully acquired and loaded
Security Framework initialized
SELinux:  Initializing.
AppArmor: AppArmor disabled by boot time parameter
Mount-cache hash table entries: 16384 (order: 5, 131072 bytes)
Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes)
Initializing cgroup subsys io
Initializing cgroup subsys freezer
Initializing cgroup subsys hugetlb
Initializing cgroup subsys debug
CPU: Physical Processor ID: 0
mce: CPU supports 32 MCE banks
Last level iTLB entries: 4KB 1024, 2MB 1024, 4MB 1024
Last level dTLB entries: 4KB 1024, 2MB 1024, 4MB 1024, 1GB 4
Spectre V2 : Mitigation: Full generic retpoline
Freeing SMP alternatives memory: 48K
..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
smpboot: CPU0: Intel(R) Xeon(R) CPU @ 2.30GHz (family: 0x6, model: 0x3f, stepping: 0x0)
Performance Events: unsupported p6 CPU model 63 no PMU driver, software events only.
x86: Booting SMP configuration:
.... node  #0, CPUs:      #1
kvm-clock: cpu 1, msr 2:1fffd041, secondary cpu clock
x86: Booted up 1 node, 2 CPUs
smpboot: Total of 2 processors activated (9200.00 BogoMIPS)
devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 512 (order: 4, 65536 bytes)
xor: automatically using best checksumming function:
kworker/u4:0 (21) used greatest stack depth: 27920 bytes left
   avx       : 21974.000 MB/sec
RTC time: 14:36:03, date: 07/17/18
NET: Registered protocol family 16
schedtune: init normalization constants...
schedtune: no energy model data
schedtune: disabled!
cpuidle: using governor ladder
cpuidle: using governor menu
ACPI: bus type PCI registered
acpiphp: ACPI Hot Plug PCI Controller Driver version: 0.5
PCI: Using configuration type 1 for base access
kworker/u4:2 (46) used greatest stack depth: 27424 bytes left
kworker/u4:2 (307) used greatest stack depth: 27024 bytes left
raid6: sse2x1   gen()  3837 MB/s
raid6: sse2x1   xor()  2265 MB/s
raid6: sse2x2   gen()  6000 MB/s
raid6: sse2x2   xor()  3710 MB/s
raid6: sse2x4   gen()  8446 MB/s
raid6: sse2x4   xor()  5084 MB/s
raid6: avx2x1   gen()  7991 MB/s
raid6: avx2x2   gen() 12792 MB/s
raid6: avx2x4   gen() 17255 MB/s
raid6: using algorithm avx2x4 gen() 17255 MB/s
raid6: using avx2x2 recovery algorithm
ACPI: Added _OSI(Module Device)
ACPI: Added _OSI(Processor Device)
ACPI: Added _OSI(3.0 _SCP Extensions)
ACPI: Added _OSI(Processor Aggregator Device)
ACPI: Executed 2 blocks of module-level executable AML code
ACPI: Interpreter enabled
ACPI: (supports S0 S3 S4 S5)
ACPI: Using IOAPIC for interrupt routing
PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug