================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 Read of size 4 at addr ffff8801d9642780 by task syz-executor4/1441 CPU: 0 PID: 1441 Comm: syz-executor4 Not tainted 4.4.153-g5e24b4e #90 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 779bb841908f7d67 ffff8801d608fcb8 ffffffff81e162ed ffffea0007659080 ffff8801d9642780 0000000000000000 ffff8801d9642780 0000000000000000 ffff8801d608fcf0 ffffffff8151b4d9 ffff8801d9642780 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 [] 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 Allocated by task 1448: [] 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 1448: [] 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 [] udp_destroy_sock+0x118/0x1a0 net/ipv4/udp.c:2056 [] 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 [] __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 ffff8801d9642780 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801d9642780, ffff8801d9642980) The buggy address belongs to the page: page:ffffea0007659080 count:1 mapcount:786445 mapping: (null) index:0x0 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 13744 Comm: syz-executor4 Not tainted 4.4.153-g5e24b4e #90 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801bb223000 task.stack: ffff8801bad98000 RIP: 0010:[] [] __rb_change_child include/linux/rbtree_augmented.h:125 [inline] RIP: 0010:[] [] __rb_rotate_set_parents lib/rbtree.c:93 [inline] RIP: 0010:[] [] __rb_insert lib/rbtree.c:181 [inline] RIP: 0010:[] [] rb_insert_color+0x1d3/0xca0 lib/rbtree.c:420 RSP: 0000:ffff8801db307b78 EFLAGS: 00010806 RAX: ffff8800a42fc870 RBX: ffffea0007659080 RCX: 1000000000000812 RDX: dffffc0000000000 RSI: ffff8801db31f610 RDI: ffffea0007659090 RBP: ffff8801db307bb8 R08: ffff8800a42fc8b0 R09: ffff8801d3ce6070 R10: 0000000000000001 R11: 0000000000025d3a R12: 8000000000004090 R13: 8000000000004080 R14: 8000000000004080 R15: ffff8800a42fc878 FS: 00000000023af940(0063) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e620000 CR3: 00000001d7b07000 CR4: 00000000001606f0 Stack: ffffed003764471b ffff8801bb2238e0 ffff8801bb223000 ffff8800a42fc870 ffff8801d3ce6078 dffffc0000000000 ffff8800a42fc860 ffffed001485f916 ffff8801db307c18 ffffffff811d8e28 0000000000000046 ffff8801bb223000 Call Trace: [] __enqueue_entity+0x138/0x230 kernel/sched/fair.c:577 [] enqueue_entity kernel/sched/fair.c:3526 [inline] [] enqueue_task_fair+0x1c6/0x2790 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_process+0x15/0x20 kernel/sched/core.c:2142 [] hrtimer_wakeup+0x48/0x60 kernel/time/hrtimer.c:1482 [] __run_hrtimer kernel/time/hrtimer.c:1261 [inline] [] __hrtimer_run_queues+0x3ad/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 [] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline] [] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151 [] spin_lock include/linux/spinlock.h:302 [inline] [] pmd_lock include/linux/mm.h:1661 [inline] [] huge_pmd_set_accessed+0xf2/0x260 mm/huge_memory.c:997 [] __handle_mm_fault mm/memory.c:3447 [inline] [] handle_mm_fault+0xd9e/0x3450 mm/memory.c:3512 [] __do_page_fault+0x365/0xa10 arch/x86/mm/fault.c:1245 [] do_page_fault+0x27/0x30 arch/x86/mm/fault.c:1308 [] page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1037 Code: 80 3c 11 00 0f 85 e6 05 00 00 4d 85 ed 48 89 03 0f 84 f6 01 00 00 4d 8d 65 10 48 ba 00 00 00 00 00 fc ff df 4c 89 e1 48 c1 e9 03 <80> 3c 11 00 0f 85 7b 06 00 00 49 3b 5d 10 0f 84 6b 04 00 00 49 RIP [] __rb_change_child include/linux/rbtree_augmented.h:125 [inline] RIP [] __rb_rotate_set_parents lib/rbtree.c:93 [inline] RIP [] __rb_insert lib/rbtree.c:181 [inline] RIP [] rb_insert_color+0x1d3/0xca0 lib/rbtree.c:420 RSP ---[ end trace f0170d96ec00809b ]---