================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 Read of size 4 at addr ffff8801d7912500 by task syz-executor7/7213 CPU: 0 PID: 7213 Comm: syz-executor7 Not tainted 4.4.152-ge15716b #24 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 9cde60826b09dfad ffff8800a405fa30 ffffffff81e15fed ffffea00075e4480 ffff8801d7912500 0000000000000000 ffff8801d7912500 0000000000000000 ffff8800a405fa68 ffffffff8151b489 ffff8801d7912500 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 [] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 [] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509 [] __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 [] get_signal+0x1190/0x14b0 kernel/signal.c:2151 [] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712 [] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:249 [] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline] [] syscall_return_slowpath arch/x86/entry/common.c:349 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline] [] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460 [] sysenter_flags_fixed+0xd/0x1a Allocated by task 7213: [] 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 [] do_syscall_32_irqs_on arch/x86/entry/common.c:393 [inline] [] do_fast_syscall_32+0x324/0x8b0 arch/x86/entry/common.c:460 [] sysenter_flags_fixed+0xd/0x1a Freed by task 7223: [] 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+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 arch/x86/entry/common.c:349 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:399 [inline] [] do_fast_syscall_32+0x61e/0x8b0 arch/x86/entry/common.c:460 [] sysenter_flags_fixed+0xd/0x1a The buggy address belongs to the object at ffff8801d7912500 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801d7912500, ffff8801d7912700) The buggy address belongs to the page: BUG: unable to handle kernel paging request at fffffffca4cd6900 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: 478 Comm: kworker/u4:3 Not tainted 4.4.152-ge15716b #24 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound call_usermodehelper_exec_work task: ffff8800bbbf1800 task.stack: ffff8800bb2c8000 RIP: 0010:[] [] cpuacct_charge+0x155/0x380 kernel/sched/cpuacct.c:247 RSP: 0018:ffff8800bb2cf898 EFLAGS: 00010046 RAX: 1ffffffff089521f RBX: 00000000000185a8 RCX: ffffffff84a16680 RDX: fffffbff9499ad20 RSI: fffffffca4cd6900 RDI: ffffffff844a90f8 RBP: ffff8800bb2cf8d8 R08: ffff8800bbbf21a0 R09: 0000000000000001 R10: 0000000000000001 R11: ffff8800bbbf1800 R12: ffffffff844a9020 R13: dffffc0000000000 R14: 000000000182658a R15: ffffffffa4058050 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffca4cd6900 CR3: 00000000a71ba000 CR4: 00000000001606f0 Stack: ffffffff81227c90 0000000000000046 0000000000000003 ffff8801d3970060 ffff8801d3970000 000000000182658a ffff8801d39700b0 0000000000000000 ffff8800bb2cf920 ffffffff811dc309 0000000000000020 ffff8800b9224800 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:2491 [] _do_fork+0x2a9/0xe20 kernel/fork.c:1814 [] kernel_thread+0x34/0x40 kernel/fork.c:1851 [] call_usermodehelper_exec_sync kernel/kmod.c:275 [inline] [] call_usermodehelper_exec_work+0xb0/0x250 kernel/kmod.c:327 [] process_one_work+0x7df/0x1600 kernel/workqueue.c:2064 [] worker_thread+0xd9/0xfc0 kernel/workqueue.c:2196 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510 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: fffffffca4cd6900 ---[ end trace dabcf78a7a5a7856 ]---