batman_adv: batadv0: Interface activated: batadv_slave_1 IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready ================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xea/0xf0 net/l2tp/l2tp_core.c:879 Read of size 4 at addr ffff88809f6ba7c0 by task syz-executor.0/7718 CPU: 0 PID: 7718 Comm: syz-executor.0 Not tainted 4.14.172-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393 l2tp_session_queue_purge+0xea/0xf0 net/l2tp/l2tp_core.c:879 l2tp_tunnel_closeall+0x1fe/0x370 net/l2tp/l2tp_core.c:1342 l2tp_udp_encap_destroy+0x8d/0xf0 net/l2tp/l2tp_core.c:1371 udpv6_destroy_sock+0xa6/0xd0 net/ipv6/udp.c:1444 sk_common_release+0x64/0x2f0 net/core/sock.c:2989 inet_release+0xdf/0x1b0 net/ipv4/af_inet.c:425 inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:450 __sock_release+0xcd/0x2b0 net/socket.c:602 sock_close+0x15/0x20 net/socket.c:1139 __fput+0x25f/0x790 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x416011 RSP: 002b:00007fffd455a7f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000416011 RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000005 RBP: 0000000000000000 R08: 00000000007703e0 R09: 01ffffffffffffff R10: 00007fffd455a8c0 R11: 0000000000000293 R12: 000000000076bf20 R13: 00000000007703e8 R14: 0000000000000000 R15: 000000000076bf2c Allocated by task 7719: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15b/0x7c0 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:661 [inline] l2tp_session_create+0x35/0x16f0 net/l2tp/l2tp_core.c:1796 pppol2tp_connect+0x1154/0x17b0 net/l2tp/l2tp_ppp.c:721 SYSC_connect+0x1c6/0x250 net/socket.c:1655 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 7719: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcb/0x260 mm/slab.c:3815 l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:300 [inline] pppol2tp_session_destruct+0xcd/0x110 net/l2tp/l2tp_ppp.c:460 __sk_destruct+0x49/0x640 net/core/sock.c:1556 sk_destruct+0x97/0xc0 net/core/sock.c:1596 __sk_free+0x4c/0x220 net/core/sock.c:1604 sk_free+0x2b/0x40 net/core/sock.c:1615 sock_put include/net/sock.h:1658 [inline] pppol2tp_release+0x247/0x2f0 net/l2tp/l2tp_ppp.c:501 __sock_release+0xcd/0x2b0 net/socket.c:602 sock_close+0x15/0x20 net/socket.c:1139 __fput+0x25f/0x790 fs/file_table.c:210 task_work_run+0x113/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff88809f6ba7c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff88809f6ba7c0, ffff88809f6ba9c0) The buggy address belongs to the page: page:ffffea00027dae80 count:1 mapcount:0 mapping:ffff88809f6ba040 index:0x0 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffff88809f6ba040 0000000000000000 0000000100000006 raw: ffffea000285d6a0 ffffea00027c8ca0 ffff88812fe56940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809f6ba680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f6ba700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff88809f6ba780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff88809f6ba800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f6ba880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================