================================================================== BUG: KASAN: use-after-free in pppol2tp_sock_to_session net/l2tp/l2tp_ppp.c:157 [inline] BUG: KASAN: use-after-free in pppol2tp_release+0x2f2/0x310 net/l2tp/l2tp_ppp.c:504 Read of size 4 at addr ffff8801d20fa000 by task syz-executor3/25113 CPU: 1 PID: 25113 Comm: syz-executor3 Not tainted 4.4.112-g3fc4284 #32 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 1fce5a3e1108be1f ffff8800b3167d00 ffffffff81d054ed ffffea0007483e80 ffff8801d20fa000 0000000000000000 ffff8801d20fa000 ffffffff82dea4d0 ffff8800b3167d38 ffffffff814fd953 ffff8801d20fa000 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 [] pppol2tp_sock_to_session net/l2tp/l2tp_ppp.c:157 [inline] [] pppol2tp_release+0x2f2/0x310 net/l2tp/l2tp_ppp.c:504 [] sock_release+0x8d/0x1e0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x233/0x6d0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x104/0x180 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x145/0x170 arch/x86/entry/common.c:251 [] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:347 [] int_ret_from_sys_call+0x25/0xa3 Allocated by task 25113: [] 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 [] __kmalloc+0x124/0x320 mm/slub.c:3613 [] kmalloc include/linux/slab.h:481 [inline] [] kzalloc include/linux/slab.h:620 [inline] [] l2tp_session_create+0x39/0x10f0 net/l2tp/l2tp_core.c:1744 [] pppol2tp_connect+0x10fc/0x1930 net/l2tp/l2tp_ppp.c:718 [] SYSC_connect+0x1b6/0x310 net/socket.c:1557 [] SyS_connect+0x24/0x30 net/socket.c:1538 [] entry_SYSCALL_64_fastpath+0x16/0x92 Freed by task 25117: [] 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] [] kfree+0xfc/0x300 mm/slub.c:3749 [] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1672 [] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline] [] l2tp_tunnel_closeall+0x2d1/0x3b0 net/l2tp/l2tp_core.c:1279 [] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300 [] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421 [] sk_common_release+0x6b/0x300 net/core/sock.c:2680 [] udp_lib_close+0x15/0x20 include/net/udp.h:190 [] inet_release+0xfa/0x1d0 net/ipv4/af_inet.c:435 [] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424 [] sock_release+0x8d/0x1e0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x233/0x6d0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x104/0x180 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x145/0x170 arch/x86/entry/common.c:251 [] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:347 [] int_ret_from_sys_call+0x25/0xa3 The buggy address belongs to the object at ffff8801d20fa000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801d20fa000, ffff8801d20fa200) 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 4.4.112-g3fc4284 (syzkaller@ci) (gcc version 7.1.1 20170620 (GCC) ) #32 SMP PREEMPT Sat Jan 20 10:36:04 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 0x0000000000100000-0x00000000bfffcfff] usable BIOS-e820: [mem 0x00000000bfffd000-0x00000000bfffffff] 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 = 0xbfffd max_arch_pfn = 0x400000000 found SMP MP-table at [mem 0x000f32c0-0x000f32cf] mapped at [ffff8800000f32c0] Scanning 1 areas for low memory corruption Using GB pages for direct mapping ACPI: Early table checksum verification disabled ACPI: RSDP 0x00000000000F3090 000014 (v00 Google) ACPI: RSDT 0x00000000BFFFDC70 000034 (v01 Google GOOGRSDT 00000001 GOOG 00000001) ACPI: FACP 0x00000000BFFFFF00 0000F4 (v02 Google GOOGFACP 00000001 GOOG 00000001) ACPI: DSDT 0x00000000BFFFDCB0 0017B2 (v01 Google GOOGDSDT 00000001 GOOG 00000001) ACPI: FACS 0x00000000BFFFFEC0 000040 ACPI: FACS 0x00000000BFFFFEC0 000040 ACPI: SSDT 0x00000000BFFFF590 000930 (v01 Google GOOGSSDT 00000001 GOOG 00000001) ACPI: APIC 0x00000000BFFFF4A0 000076 (v01 Google GOOGAPIC 00000001 GOOG 00000001) ACPI: WAET 0x00000000BFFFF470 000028 (v01 Google GOOGWAET 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 1990833765 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 0x0000000000100000-0x00000000bfffcfff] 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 0xbfffd000-0xbfffffff] 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: 1935237 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: 6581452K/7863916K available (40431K kernel code, 6131K rwdata, 8808K rodata, 1848K init, 23616K bss, 1282464K 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 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.