================================================================== BUG: KASAN: use-after-free in pppol2tp_connect+0x160a/0x1910 net/l2tp/l2tp_ppp.c:735 Read of size 8 at addr ffff8800b53f9090 by task syz-executor0/8017 CPU: 0 PID: 8017 Comm: syz-executor0 Not tainted 4.4.152-ge5c5f1f #89 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 c5b48cd05b56ed1a ffff8800a1c8fb28 ffffffff81e15fed ffffea0002d4fe00 ffff8800b53f9090 0000000000000000 ffff8800b53f9090 ffff8800a1c8fd50 ffff8800a1c8fb60 ffffffff8151b489 ffff8800b53f9090 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_load8_noabort+0x14/0x20 mm/kasan/report.c:429 [] pppol2tp_connect+0x160a/0x1910 net/l2tp/l2tp_ppp.c:735 [] SYSC_connect+0x1b8/0x300 net/socket.c:1570 [] SyS_connect+0x24/0x30 net/socket.c:1551 [] entry_SYSCALL_64_fastpath+0x22/0x9e Allocated by task 8017: [] 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:1570 [] SyS_connect+0x24/0x30 net/socket.c:1551 [] entry_SYSCALL_64_fastpath+0x22/0x9e Freed by task 8016: [] 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] [] pppol2tp_session_destruct+0xd7/0x110 net/l2tp/l2tp_ppp.c:477 [] 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+0xd9/0x260 net/socket.c:592 [] sock_close+0x19/0x20 net/socket.c:1050 [] __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:253 [] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:349 [] int_ret_from_sys_call+0x25/0xa3 The buggy address belongs to the object at ffff8800b53f8f00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff8800b53f8f00, ffff8800b53f9100) The buggy address belongs to the page: BUG: unable to handle kernel paging request at fffffffb8ee979b8 IP: [] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247 PGD 440f067 PUD 0 Oops: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 7395 Comm: getty Not tainted 4.4.152-ge5c5f1f #89 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b14b4800 task.stack: ffff8801d8ca0000 RIP: 0010:[] [] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247 RSP: 0018:ffff8801d8ca78f8 EFLAGS: 00010046 RAX: 1ffffffff089521f RBX: 00000000000185a8 RCX: ffffffff84a16680 RDX: fffffbff71dd2f37 RSI: fffffffb8ee979b8 RDI: ffffffff844a90f8 RBP: ffff8801d8ca7938 R08: ffff8800b14b51a0 R09: 0000000000000001 R10: 0000000000000001 R11: ffff8800b14b4800 R12: ffffffff844a9020 R13: dffffc0000000000 R14: 0000000016fa9b4a R15: ffffffff81490267 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffb8ee979b8 CR3: 000000000440c000 CR4: 00000000001606f0 Stack: ffffffff81227c90 0000000000000046 0000000000000003 ffff8801d2a49860 ffff8801d2a49800 0000000016fa9b4a ffff8801d2a498b0 0000000000000000 ffff8801d8ca7980 ffffffff811dc309 0000000000000005 ffff8801db21f558 Call Trace: [] update_curr+0x2c9/0x6d0 kernel/sched/fair.c:882 [] enqueue_entity kernel/sched/fair.c:3512 [inline] [] enqueue_task_fair+0x2fa/0x2790 kernel/sched/fair.c:4695 [] enqueue_task kernel/sched/core.c:858 [inline] [] activate_task+0x14d/0x280 kernel/sched/core.c:874 [] ttwu_activate kernel/sched/core.c:1736 [inline] [] ttwu_do_activate.constprop.109+0xbf/0x1e0 kernel/sched/core.c:1789 [] ttwu_queue kernel/sched/core.c:1934 [inline] [] try_to_wake_up+0x660/0xf00 kernel/sched/core.c:2068 [] wake_up_state+0x10/0x20 kernel/sched/core.c:2148 [] signal_wake_up_state+0x44/0x70 kernel/signal.c:659 [] signal_wake_up include/linux/sched.h:3332 [inline] [] complete_signal+0x48b/0x790 kernel/signal.c:952 [] __send_signal+0x4d5/0x11b0 kernel/signal.c:1080 [] send_signal+0x4a/0xc0 kernel/signal.c:1096 [] __group_send_sig_info kernel/signal.c:1135 [inline] [] do_notify_parent+0xaee/0xd50 kernel/signal.c:1669 [] exit_notify kernel/exit.c:612 [inline] [] do_exit+0x1f75/0x26b0 kernel/exit.c:776 [] do_group_exit+0x111/0x330 kernel/exit.c:885 [] SYSC_exit_group kernel/exit.c:896 [inline] [] SyS_exit_group+0x1d/0x20 kernel/exit.c:894 [] entry_SYSCALL_64_fastpath+0x22/0x9e Code: 49 8d bc 24 d8 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 c4 01 00 00 49 8b 9c 24 d8 00 00 00 80 3a 00 0f 85 8f 01 00 00 <4a> 03 1c f9 48 89 d8 48 c1 e8 03 42 80 3c 28 00 0f 85 be 01 00 RIP [] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247 RSP CR2: fffffffb8ee979b8 ---[ end trace 0cfde1fef88b2969 ]---