================================================================== BUG: KASAN: use-after-free in pppol2tp_connect+0x160a/0x1910 net/l2tp/l2tp_ppp.c:735 Read of size 8 at addr ffff8800bb3b7090 by task syz-executor0/15222 CPU: 1 PID: 15222 Comm: syz-executor0 Not tainted 4.4.140-g789274d #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 17ac396254dcc7c2 ffff8800ac2efab0 ffffffff81e0e08d ffffea0002eced80 ffff8800bb3b7090 0000000000000000 ffff8800bb3b7090 ffff8800ac2efcd8 ffff8800ac2efae8 ffffffff81515a56 ffff8800bb3b7090 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:1557 [] SyS_connect+0x24/0x30 net/socket.c:1538 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 Allocated by task 15219: [] 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 [] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline] [] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 Freed by task 15215: [] 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+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 arch/x86/entry/common.c:348 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:398 [inline] [] do_fast_syscall_32+0x620/0x8b0 arch/x86/entry/common.c:459 [] sysenter_flags_fixed+0xd/0x17 The buggy address belongs to the object at ffff8800bb3b6f00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 400 bytes inside of 512-byte region [ffff8800bb3b6f00, ffff8800bb3b7100) The buggy address belongs to the page: BUG: unable to handle kernel paging request at fffffffce6155140 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: 0 PID: 15147 Comm: udevd Not tainted 4.4.140-g789274d #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800ac56e000 task.stack: ffff8801d2f10000 RIP: 0010:[] [] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247 RSP: 0018:ffff8801d2f17c28 EFLAGS: 00010046 RAX: 1ffffffff089500f RBX: 0000000000018528 RCX: ffffffff84a14ec0 RDX: fffffbff9cc2aa28 RSI: fffffffce6155140 RDI: ffffffff844a8078 RBP: ffff8801d2f17c68 R08: ffff8800ac56e950 R09: 0000000000000001 R10: 0000000000000001 R11: ffff8800ac56e000 R12: ffffffff844a7fa0 R13: dffffc0000000000 R14: 00000000017e0f7a R15: ffffffffac2e8050 FS: 00007f5982fb87a0(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffce6155140 CR3: 00000001c8736000 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff81224c00 0000000000000046 0000000000000003 ffff8801d4f4c860 ffff8801d4f4c800 00000000017e0f7a ffff8801d4f4c8b0 0000000000000000 ffff8801d2f17cb0 ffffffff811d9279 0000000000000020 ffff8801c795c800 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 [] wake_up_new_task+0x647/0xe30 kernel/sched/core.c:2495 [] _do_fork+0x2a1/0xe10 kernel/fork.c:1808 [] SYSC_clone kernel/fork.c:1893 [inline] [] SyS_clone+0x37/0x50 kernel/fork.c:1887 [] 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: fffffffce6155140 ---[ end trace bc191e0b55e419b6 ]---