==================================================================
BUG: KASAN: use-after-free in link_path_walk+0x1375/0x1710 fs/namei.c:1949
Read of size 4 at addr ffff88009e8ade40 by task syz-executor7/31850

CPU: 1 PID: 31850 Comm: syz-executor7 Not tainted 4.4.132-gecf86dd #46
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 281351a0bc8b43c0 ffff8800b24ff910 ffffffff81e0df8d
 ffffea00027a2b00 ffff88009e8ade40 0000000000000000 ffff88009e8ade40
 ffff8800b24ffcf0 ffff8800b24ff948 ffffffff8151526c ffff88009e8ade40
Call Trace:
 [<ffffffff81e0df8d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0df8d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8151526c>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff8151558b>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8151558b>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9064>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff8154a3b5>] link_path_walk+0x1375/0x1710 fs/namei.c:1949
 [<ffffffff8154b684>] path_openat+0x1a4/0x3a10 fs/namei.c:3358
 [<ffffffff81551c07>] do_filp_open+0x197/0x270 fs/namei.c:3393
 [<ffffffff8151b2cc>] do_sys_open+0x31c/0x610 fs/open.c:1038
 [<ffffffff8151b630>] SYSC_openat fs/open.c:1065 [inline]
 [<ffffffff8151b630>] SyS_openat+0x30/0x40 fs/open.c:1059
 [<ffffffff838c0225>] entry_SYSCALL_64_fastpath+0x22/0x9e

Allocated by task 31807:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8133>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8417>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8417>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f89e2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f44de>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f44de>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f44de>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f44de>] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628
 [<ffffffff8156a0de>] __d_alloc+0x2e/0x7b0 fs/dcache.c:1589
 [<ffffffff8156ab07>] d_make_root+0x47/0x90 fs/dcache.c:1934
 [<ffffffff8184197d>] ramfs_fill_super+0x35d/0x490 fs/ramfs/inode.c:232
 [<ffffffff8152632b>] mount_nodev+0x5b/0x100 fs/super.c:1086
 [<ffffffff81840e1c>] ramfs_mount+0x2c/0x40 fs/ramfs/inode.c:242
 [<ffffffff8152835c>] mount_fs+0x28c/0x370 fs/super.c:1146
 [<ffffffff815800f1>] vfs_kern_mount.part.30+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff8158773e>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff8158773e>] do_new_mount fs/namespace.c:2517 [inline]
 [<ffffffff8158773e>] do_mount+0x4ee/0x2860 fs/namespace.c:2833
 [<ffffffff8158a4c0>] SYSC_mount fs/namespace.c:3027 [inline]
 [<ffffffff8158a4c0>] SyS_mount+0x130/0x1d0 fs/namespace.c:3005
 [<ffffffff838c0225>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 31807:
 [<ffffffff810341d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8133>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8a62>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8a62>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f5bee>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f5bee>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f5bee>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f5bee>] kmem_cache_free+0xbe/0x340 mm/slub.c:2881
 [<ffffffff81561855>] __d_free fs/dcache.c:257 [inline]
 [<ffffffff81561855>] dentry_free+0xd5/0x150 fs/dcache.c:333
 [<ffffffff8156389c>] __dentry_kill+0x4ac/0x5f0 fs/dcache.c:576
 [<ffffffff81567177>] dentry_kill fs/dcache.c:603 [inline]
 [<ffffffff81567177>] dput.part.26+0x587/0x760 fs/dcache.c:818
 [<ffffffff815691c3>] dput fs/dcache.c:782 [inline]
 [<ffffffff815691c3>] do_one_tree+0x43/0x50 fs/dcache.c:1473
 [<ffffffff81569fe2>] shrink_dcache_for_umount+0x62/0x130 fs/dcache.c:1487
 [<ffffffff8152397d>] generic_shutdown_super+0x6d/0x300 fs/super.c:413
 [<ffffffff81524202>] kill_anon_super fs/super.c:914 [inline]
 [<ffffffff81524202>] kill_litter_super+0x72/0x90 fs/super.c:924
 [<ffffffff81840ddf>] ramfs_kill_sb+0x3f/0x50 fs/ramfs/inode.c:248
 [<ffffffff815246dd>] deactivate_locked_super+0x8d/0xd0 fs/super.c:301
 [<ffffffff81525021>] deactivate_super+0x91/0xd0 fs/super.c:332
 [<ffffffff8157f3a2>] cleanup_mnt+0xb2/0x160 fs/namespace.c:1119
 [<ffffffff8157f4d6>] __cleanup_mnt+0x16/0x20 fs/namespace.c:1126
 [<ffffffff8118bb8f>] 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:252
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838c03b5>] int_ret_from_sys_call+0x25/0xa3

The buggy address belongs to the object at ffff88009e8ade40
 which belongs to the cache dentry of size 288
The buggy address is located 0 bytes inside of
 288-byte region [ffff88009e8ade40, ffff88009e8adf60)
The buggy address belongs to the page:
BUG: unable to handle kernel paging request at ffffeafffe0e8000
IP: [<ffffffff8150a3d9>] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline]
SeaBIOS (version 1.8.2-20171130_102032-google)
IP: [<ffffffff8150a3d9>] PageHead include/linux/page-flags.h:396 [inline]
SeaBIOS (version 1.8.2-20171130_102032-google)
IP: [<ffffffff8150a3d9>] PageCompound include/linux/page-flags.h:424 [inline]
SeaBIOS (version 1.8.2-20171130_102032-google)
IP: [<ffffffff8150a3d9>] do_huge_pmd_wp_page+0x669/0x1560 mm/huge_memory.c:1172
SeaBIOS (version 1.8.2-20171130_102032-google)
Initializing cgroup subsys cpuset
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Initializing cgroup subsys schedtune
Linux version 4.4.132-gecf86dd (syzkaller@ci) (gcc version 8.0.1 20180413 (experimental) (GCC) ) #46 SMP PREEMPT Wed May 23 06:07:50 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 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.
x86/fpu: Using 'eager' FPU context switches.
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 0x000f23d0-0x000f23df] mapped at [ffff8800000f23d0]
Scanning 1 areas for low memory corruption
Using GB pages for direct mapping
ACPI: Early table checksum verification disabled
ACPI: RSDP 0x00000000000F2390 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 2524793757 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 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 (41752K kernel code, 6301K rwdata, 9048K 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: 27424 bytes left
   avx       : 21511.600 MB/sec
RTC time:  9:59:08, date: 05/23/18
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/u4:0 (372) used greatest stack depth: 27024 bytes left
raid6: sse2x1   gen()  4408 MB/s
raid6: sse2x1   xor()  2469 MB/s
raid6: sse2x2   gen()  6642 MB/s
raid6: sse2x2   xor()  3798 MB/s
raid6: sse2x4   gen()  8675 MB/s
raid6: sse2x4   xor()  5006 MB/s
raid6: avx2x1   gen()  7867 MB/s
raid6: avx2x2   gen() 12415 MB/s
raid6: avx2x4   gen() 17557 MB/s
raid6: using algorithm avx2x4 gen() 17557 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
ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI]
acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM
acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge.
PCI host bridge to bus 0000:00
pci_bus 0000:00: root bus resource [io  0x0000-0x0cf7 window]
pci_bus 0000:00: root bus resource [io  0x0d00-0xffff window]
pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window]
pci_bus 0000:00: root bus resource [mem 0xc0000000-0xfebfffff window]
pci_bus 0000:00: root bus resource [bus 00-ff]
pci 0000:00:01.3: quirk: [io  0xb000-0xb03f] claimed by PIIX4 ACPI
ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)
ACPI: PCI Interrupt Link [LNKB] (IRQs 5 *10 11)
ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)
ACPI: PCI Interrupt Link [LNKD] (IRQs 5 10 *11)
ACPI: PCI Interrupt Link [LNKS] (IRQs *9)