sd 0:0:1:0: [sg0] tag#899 CDB[20]: 1e 14 70 af f6 2d 3a 14 19 47 03 bb 74 e5 bf 10 sd 0:0:1:0: [sg0] tag#899 CDB[30]: 9d 13 d3 4e a6 18 0a 39 5e 0c 9b fd 4d a2 2f a9 sd 0:0:1:0: [sg0] tag#899 CDB[40]: 87 a0 97 39 f7 05 54 01 18 e6 cd 00 b7 e9 a0 29 sd 0:0:1:0: [sg0] tag#899 CDB[50]: 65 68 5d 81 0a 19 4f b1 15 f3 3b 81 bf fe ac a1 ================================================================== BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xf2/0x110 net/l2tp/l2tp_ppp.c:476 Read of size 4 at addr ffff8800acfb0a00 by task syz-executor3/25312 CPU: 1 PID: 25312 Comm: syz-executor3 Not tainted 4.4.136-gfb7e319 #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 be133dfa4c4509a4 ffff8800b09efc68 ffffffff81e0edad ffffea0002b3ec00 ffff8800acfb0a00 0000000000000000 ffff8800acfb0a00 ffffffff82f1a280 ffff8800b09efca0 ffffffff815159b6 ffff8800acfb0a00 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_address_description+0x6c/0x216 mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408 [] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428 [] pppol2tp_session_destruct+0xf2/0x110 net/l2tp/l2tp_ppp.c:476 [] sk_destruct+0x4c/0x4c0 net/core/sock.c:1447 [] __sk_free+0x4f/0x220 net/core/sock.c:1480 [] sk_free+0x30/0x40 net/core/sock.c:1491 [] sock_put include/net/sock.h:1639 [inline] [] pppol2tp_release+0x26a/0x310 net/l2tp/l2tp_ppp.c:518 [] sock_release+0x96/0x1c0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x235/0x6f0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10f/0x190 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+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 Allocated by task 25312: [] 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+0xc7/0xe0 mm/kasan/kasan.c:616 [] __kmalloc+0x124/0x310 mm/slub.c:3613 [] kmalloc include/linux/slab.h:481 [inline] [] kzalloc include/linux/slab.h:620 [inline] [] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748 [] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725 [] SYSC_connect+0x1b8/0x300 net/socket.c:1557 [] SyS_connect+0x24/0x30 net/socket.c:1538 [] entry_SYSCALL_64_fastpath+0x22/0x9e Freed by task 25314: [] 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+0xf4/0x310 mm/slub.c:3749 [] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676 [] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline] [] l2tp_tunnel_closeall+0x2b9/0x350 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+0x6d/0x300 net/core/sock.c:2680 [] udp_lib_close+0x15/0x20 include/net/udp.h:190 [] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435 [] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424 [] sock_release+0x96/0x1c0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x235/0x6f0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10f/0x190 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+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 The buggy address belongs to the object at ffff8800acfb0a00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8800acfb0a00, ffff8800acfb0c00) The buggy address belongs to the page: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.136-gfb7e319 #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffffffff84417840 task.stack: ffffffff84400000 RIP: 0010:[] [] timerqueue_add+0xb8/0x2b0 lib/timerqueue.c:51 RSP: 0018:ffff8801db207d30 EFLAGS: 00010007 RAX: ffffed003b64338b RBX: ffff8801db219c40 RCX: 0000000000000000 RDX: 000000001083e1e8 RSI: ffffffff81e2c6fc RDI: 00000000841f0f46 RBP: ffff8801db207d70 R08: 0000000000000096 R09: 0000000000000001 R10: 0000000000000000 R11: ffffffff84417840 R12: dffffc0000000000 R13: 00000000841f0f2e R14: 0000005f1f7a4580 R15: ffffffff8148cf87 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001255f10 CR3: 00000000b65af000 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8801db219c58 ffff8801db219710 ffffed003b64338b ffff8801db219700 ffff8801db219c40 ffff8801db219640 0000000000000001 0000000000000000 ffff8801db207da8 ffffffff8129b35f ffff8801db219c40 0000000000000001 Call Trace: [] enqueue_hrtimer+0x15f/0x440 kernel/time/hrtimer.c:893 [] __run_hrtimer kernel/time/hrtimer.c:1276 [inline] [] __hrtimer_run_queues+0x6b2/0x1000 kernel/time/hrtimer.c:1325 [] hrtimer_interrupt+0x1b1/0x430 kernel/time/hrtimer.c:1359 [] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:901 [] smp_apic_timer_interrupt+0x7c/0xa0 arch/x86/kernel/apic/apic.c:925 [] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:741 [] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline] [] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290 [] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281 [] default_idle_call+0x57/0x70 kernel/sched/idle.c:93 [] cpuidle_idle_call kernel/sched/idle.c:157 [inline] [] cpu_idle_loop kernel/sched/idle.c:253 [inline] [] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301 [] rest_init+0x188/0x18e init/main.c:410 [] start_kernel+0x6b3/0x6e7 init/main.c:682 [] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196 [] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:185 Code: 00 00 4d 8b 2f 4d 85 ed 74 3d e8 b4 4d 52 ff 48 8b 45 d0 80 38 00 0f 85 96 01 00 00 49 8d 7d 18 4c 8b 73 18 48 89 fa 48 c1 ea 03 <42> 80 3c 22 00 0f 85 8a 01 00 00 4d 3b 75 18 7c a3 e8 82 4d 52 RIP [] timerqueue_add+0xb8/0x2b0 lib/timerqueue.c:51 RSP ---[ end trace 4d70c2b708d4f88b ]---