================================================================== BUG: KASAN: use-after-free in link_path_walk+0x137a/0x14f0 fs/namei.c:1948 Read of size 4 at addr ffff8801d2dbbce0 by task syz-executor4/17946 CPU: 1 PID: 17946 Comm: syz-executor4 Not tainted 4.4.125-g38f41ec #21 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 604dc87538838795 ffff8800b53cf890 ffffffff81d067bd ffffea00074b6e80 ffff8801d2dbbce0 0000000000000000 ffff8801d2dbbce0 ffff8801d2dbbce0 ffff8800b53cf8c8 ffffffff814fea83 ffff8801d2dbbce0 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_address_description+0x73/0x260 mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report+0x285/0x370 mm/kasan/report.c:408 [] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428 [] link_path_walk+0x137a/0x14f0 fs/namei.c:1948 [] path_openat+0x19f/0x3940 fs/namei.c:3357 [] do_filp_open+0x197/0x290 fs/namei.c:3392 [] do_sys_open+0x369/0x660 fs/open.c:1038 [] C_SYSC_open fs/compat.c:1092 [inline] [] compat_SyS_open+0x2a/0x40 fs/compat.c:1090 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 Allocated by task 17946: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:616 [] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554 [] slab_post_alloc_hook mm/slub.c:1349 [inline] [] slab_alloc_node mm/slub.c:2615 [inline] [] slab_alloc mm/slub.c:2623 [inline] [] kmem_cache_alloc+0xba/0x290 mm/slub.c:2628 [] __d_alloc+0x2e/0x7b0 fs/dcache.c:1589 [] d_make_root+0x44/0x90 fs/dcache.c:1934 [] ramfs_fill_super+0x35f/0x4a0 fs/ramfs/inode.c:232 [] mount_nodev+0x59/0x100 fs/super.c:1086 [] ramfs_mount+0x2c/0x40 fs/ramfs/inode.c:242 [] mount_fs+0x27f/0x350 fs/super.c:1146 [] vfs_kern_mount.part.21+0xd0/0x3e0 fs/namespace.c:991 [] vfs_kern_mount fs/namespace.c:2508 [inline] [] do_new_mount fs/namespace.c:2516 [inline] [] do_mount+0xe8e/0x2900 fs/namespace.c:2832 [] C_SYSC_mount fs/compat.c:824 [inline] [] compat_SyS_mount+0x106/0x1180 fs/compat.c:789 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x321/0x8a0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 Freed by task 17952: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589 [] slab_free_hook mm/slub.c:1383 [inline] [] slab_free_freelist_hook mm/slub.c:1405 [inline] [] slab_free mm/slub.c:2859 [inline] [] kmem_cache_free+0xc7/0x320 mm/slub.c:2881 [] __d_free fs/dcache.c:257 [inline] [] dentry_free+0xd5/0x150 fs/dcache.c:333 [] __dentry_kill+0x491/0x620 fs/dcache.c:576 [] dentry_kill fs/dcache.c:603 [inline] [] dput.part.19+0x638/0x760 fs/dcache.c:818 [] dput fs/dcache.c:782 [inline] [] do_one_tree+0x43/0x50 fs/dcache.c:1473 [] shrink_dcache_for_umount+0x67/0x140 fs/dcache.c:1487 [] generic_shutdown_super+0x6d/0x340 fs/super.c:413 [] kill_anon_super fs/super.c:914 [inline] [] kill_litter_super+0x72/0x90 fs/super.c:924 [] ramfs_kill_sb+0x3f/0x50 fs/ramfs/inode.c:248 [] deactivate_locked_super+0x88/0xd0 fs/super.c:301 [] deactivate_super+0x91/0xd0 fs/super.c:332 [] cleanup_mnt+0xb2/0x160 fs/namespace.c:1118 [] __cleanup_mnt+0x16/0x20 fs/namespace.c:1125 [] task_work_run+0x104/0x180 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:252 [] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline] [] syscall_return_slowpath arch/x86/entry/common.c:348 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline] [] do_fast_syscall_32+0x614/0x8a0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 The buggy address belongs to the object at ffff8801d2dbbce0 which belongs to the cache dentry of size 288 The buggy address is located 0 bytes inside of 288-byte region [ffff8801d2dbbce0, ffff8801d2dbbe00) The buggy address belongs to the page: ------------[ cut here ]------------ Initializing cgroup subsys cpuset Initializing cgroup subsys cpu Initializing cgroup subsys cpuacct Initializing cgroup subsys schedtune Linux version 4.4.125-g38f41ec (syzkaller@ci) (gcc version 7.1.1 20170620 (GCC) ) #21 SMP PREEMPT Thu Mar 29 11:51:28 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=120 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 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 2321168482 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=120 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: 6581380K/7863876K available (40445K kernel code, 6140K rwdata, 8816K rodata, 1852K init, 23632K bss, 1282496K reserved, 0K cma-reserved) SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1 Kernel/User page tables isolation: enabled 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 : Vulnerable: Minimal generic ASM retpoline Freeing SMP alternatives memory: 44K ..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: 27944 bytes left avx : 21226.800 MB/sec RTC time: 2:50:06, date: 04/23/18 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 (45) used greatest stack depth: 27448 bytes left raid6: sse2x1 gen() 4591 MB/s raid6: sse2x1 xor() 2575 MB/s raid6: sse2x2 gen() 7562 MB/s raid6: sse2x2 xor() 4317 MB/s raid6: sse2x4 gen() 8989 MB/s raid6: sse2x4 xor() 5608 MB/s raid6: avx2x1 gen() 9421 MB/s raid6: avx2x2 gen() 14651 MB/s raid6: avx2x4 gen() 19051 MB/s raid6: using algorithm avx2x4 gen() 19051 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)