================================================================== BUG: KASAN: use-after-free in debug_spin_lock_after kernel/locking/spinlock_debug.c:91 [inline] BUG: KASAN: use-after-free in do_raw_spin_lock+0x1b9/0x1e0 kernel/locking/spinlock_debug.c:114 Write of size 4 at addr ffff8801d89487e0 by task syzkaller256349/3682 CPU: 1 PID: 3682 Comm: syzkaller256349 Not tainted 4.9.80-g8a174b47 #39 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d882fc08 ffffffff81d94be9 ffffea0007625200 ffff8801d89487e0 0000000000000001 ffff8801d89487e0 ffff8801d8948900 ffff8801d882fc40 ffffffff8153e113 ffff8801d89487e0 0000000000000004 0000000000000001 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x73/0x280 mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report+0x275/0x360 mm/kasan/report.c:408 [] __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:433 [] debug_spin_lock_after kernel/locking/spinlock_debug.c:91 [inline] [] do_raw_spin_lock+0x1b9/0x1e0 kernel/locking/spinlock_debug.c:114 [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:119 [inline] [] _raw_spin_lock_irqsave+0x56/0x70 kernel/locking/spinlock.c:159 [] skb_dequeue+0x22/0x180 net/core/skbuff.c:2380 [] l2tp_session_queue_purge+0xab/0x100 net/l2tp/l2tp_core.c:918 [] pppol2tp_release+0x1ff/0x2e0 net/l2tp/l2tp_ppp.c:492 [] sock_release+0x8d/0x1e0 net/socket.c:599 [] sock_close+0x16/0x20 net/socket.c:1046 [] __fput+0x28c/0x6e0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x115/0x190 kernel/task_work.c:116 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:160 [] prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] [] syscall_return_slowpath arch/x86/entry/common.c:259 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] [] do_fast_syscall_32+0x5de/0x890 arch/x86/entry/common.c:384 [] entry_SYSENTER_compat+0x74/0x83 arch/x86/entry/entry_64_compat.S:127 Allocated by task 3681: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:609 __kmalloc+0x11d/0x310 mm/slub.c:3741 kmalloc include/linux/slab.h:495 [inline] kzalloc include/linux/slab.h:636 [inline] l2tp_session_create+0x38/0x1770 net/l2tp/l2tp_core.c:1839 pppol2tp_connect+0x10fe/0x18f0 net/l2tp/l2tp_ppp.c:711 SYSC_connect+0x1b6/0x310 net/socket.c:1562 SyS_connect+0x24/0x30 net/socket.c:1543 do_syscall_32_irqs_on arch/x86/entry/common.c:322 [inline] do_fast_syscall_32+0x2f7/0x890 arch/x86/entry/common.c:384 entry_SYSENTER_compat+0x74/0x83 arch/x86/entry/entry_64_compat.S:127 Freed by task 3681: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2958 [inline] kfree+0x103/0x300 mm/slub.c:3878 l2tp_session_free+0x166/0x200 net/l2tp/l2tp_core.c:1766 l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:297 [inline] l2tp_tunnel_closeall+0x26c/0x3a0 net/l2tp/l2tp_core.c:1373 l2tp_udp_encap_destroy+0x87/0xe0 net/l2tp/l2tp_core.c:1394 udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1336 sk_common_release+0x6b/0x2f0 net/core/sock.c:2727 udp_lib_close+0x15/0x20 include/net/udp.h:203 inet_release+0xfa/0x1d0 net/ipv4/af_inet.c:434 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:437 sock_release+0x8d/0x1e0 net/socket.c:599 sock_close+0x16/0x20 net/socket.c:1046 __fput+0x28c/0x6e0 fs/file_table.c:208 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x115/0x190 kernel/task_work.c:116 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] syscall_return_slowpath arch/x86/entry/common.c:259 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] do_fast_syscall_32+0x5de/0x890 arch/x86/entry/common.c:384 entry_SYSENTER_compat+0x74/0x83 arch/x86/entry/entry_64_compat.S:127 The buggy address belongs to the object at ffff8801d8948780 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 96 bytes inside of 512-byte region [ffff8801d8948780, ffff8801d8948980) The buggy address belongs to the page: page:ffffea0007625200 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x8000000000004080(slab|head) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d8948680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d8948700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801d8948780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801d8948800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d8948880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================