================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 Read of size 4 at addr ffff8801d131e000 by task syz-executor1/21428 CPU: 1 PID: 21428 Comm: syz-executor1 Not tainted 4.4.152-ge5c5f1f #89 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 99480b6aa4c57190 ffff8801baf17a78 ffffffff81e15fed ffffea000744c780 ffff8801d131e000 0000000000000000 ffff8801d131e000 0000000000000000 ffff8801baf17ab0 ffffffff8151b489 ffff8801d131e000 Call Trace: [<ffffffff81e15fed>] __dump_stack lib/dump_stack.c:15 [inline] [<ffffffff81e15fed>] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [<ffffffff8151b489>] print_address_description+0x6c/0x216 mm/kasan/report.c:252 [<ffffffff8151b7a8>] kasan_report_error mm/kasan/report.c:351 [inline] [<ffffffff8151b7a8>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408 [<ffffffff814fe714>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428 [<ffffffff835a4b64>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 [<ffffffff835b166f>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509 [<ffffffff82f210c9>] __sock_release+0xd9/0x260 net/socket.c:592 [<ffffffff82f21269>] sock_close+0x19/0x20 net/socket.c:1050 [<ffffffff81528875>] __fput+0x235/0x6f0 fs/file_table.c:208 [<ffffffff81528db5>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff8118ee4f>] task_work_run+0x10f/0x190 kernel/task_work.c:115 [<ffffffff81162290>] get_signal+0x1190/0x14b0 kernel/signal.c:2151 [<ffffffff8100df4b>] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712 [<ffffffff8100360a>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:249 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline] [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:349 [<ffffffff838cc6f5>] int_ret_from_sys_call+0x25/0xa3 Allocated by task 21417: [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [<ffffffff814fd7d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [<ffffffff814fdab7>] set_track mm/kasan/kasan.c:524 [inline] [<ffffffff814fdab7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616 [<ffffffff814fa1f4>] __kmalloc+0x124/0x310 mm/slub.c:3613 [<ffffffff835a9f79>] kmalloc include/linux/slab.h:481 [inline] [<ffffffff835a9f79>] kzalloc include/linux/slab.h:620 [inline] [<ffffffff835a9f79>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748 [<ffffffff835aec80>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725 [<ffffffff82f27bf8>] SYSC_connect+0x1b8/0x300 net/socket.c:1570 [<ffffffff82f2a544>] SyS_connect+0x24/0x30 net/socket.c:1551 [<ffffffff838cc565>] entry_SYSCALL_64_fastpath+0x22/0x9e Freed by task 21417: [<ffffffff81034676>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [<ffffffff814fd7d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [<ffffffff814fe102>] set_track mm/kasan/kasan.c:524 [inline] [<ffffffff814fe102>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589 [<ffffffff814fb664>] slab_free_hook mm/slub.c:1383 [inline] [<ffffffff814fb664>] slab_free_freelist_hook mm/slub.c:1405 [inline] [<ffffffff814fb664>] slab_free mm/slub.c:2859 [inline] [<ffffffff814fb664>] kfree+0xf4/0x310 mm/slub.c:3749 [<ffffffff835a6ee0>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676 [<ffffffff835a9299>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline] [<ffffffff835a9299>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279 [<ffffffff835a9dab>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300 [<ffffffff8349bc11>] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421 [<ffffffff82f38add>] sk_common_release+0x6d/0x300 net/core/sock.c:2680 [<ffffffff8349a8c5>] udp_lib_close+0x15/0x20 include/net/udp.h:190 [<ffffffff8330244f>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435 [<ffffffff83424ec0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424 [<ffffffff82f210c9>] __sock_release+0xd9/0x260 net/socket.c:592 [<ffffffff82f21269>] sock_close+0x19/0x20 net/socket.c:1050 [<ffffffff81528875>] __fput+0x235/0x6f0 fs/file_table.c:208 [<ffffffff81528db5>] ____fput+0x15/0x20 fs/file_table.c:244 [<ffffffff8118ee4f>] task_work_run+0x10f/0x190 kernel/task_work.c:115 [<ffffffff8100362d>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<ffffffff8100362d>] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:253 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:284 [inline] [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:349 [<ffffffff838cc6f5>] int_ret_from_sys_call+0x25/0xa3 The buggy address belongs to the object at ffff8801d131e000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801d131e000, ffff8801d131e200) The buggy address belongs to the page: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 3775 Comm: syz-executor5 Not tainted 4.4.152-ge5c5f1f #89 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801cd783000 task.stack: ffff8801bf680000 RIP: 0010:[<ffffffff81e77667>] [<ffffffff81e77667>] lookup_object lib/debugobjects.c:120 [inline] RIP: 0010:[<ffffffff81e77667>] [<ffffffff81e77667>] debug_object_activate+0x1b7/0x480 lib/debugobjects.c:405 RSP: 0018:ffff8801bf687a10 EFLAGS: 00010806 RAX: dffffc0000000000 RBX: dbe00164000053a9 RCX: ffffffff859a60a8 RDX: 1b7c002c80000a78 RSI: 0000000000000008 RDI: dbe00164000053c1 RBP: ffff8801bf687ac8 R08: 0000000000000096 R09: 0000000000000001 R10: 0000000000000001 R11: ffff8801cd783000 R12: 1ffff10037ed0f44 R13: ffff8800b3282378 R14: 0000000000000014 R15: ffffffff844beb80 FS: 0000000000ab4940(0063) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8ae8cd4000 CR3: 00000001bf5df000 CR4: 00000000001606f0 Stack: 0000000000000096 ffffffff859a60a8 0000000041b58ab3 ffffffff8420c43f ffffffff81e774b0 00000000cd7838d8 0000000000000000 0000000000000000 0000000000000005 ffff8800b3282378 ffffffff844beb80 dffffc0000000000 Call Trace: [<ffffffff81287945>] debug_rcu_head_queue kernel/rcu/rcu.h:75 [inline] [<ffffffff81287945>] __call_rcu.constprop.66+0x35/0x930 kernel/rcu/tree.c:3059 [<ffffffff81288252>] call_rcu+0x12/0x20 kernel/rcu/tree_plugin.h:662 [<ffffffff81c5901d>] avc_node_delete+0xdd/0x130 security/selinux/avc.c:496 [<ffffffff81c59f5d>] avc_reclaim_node security/selinux/avc.c:533 [inline] [<ffffffff81c59f5d>] avc_alloc_node+0x1fd/0x3d0 security/selinux/avc.c:561 [<ffffffff81c5ac38>] avc_insert security/selinux/avc.c:672 [inline] [<ffffffff81c5ac38>] avc_compute_av+0x178/0x610 security/selinux/avc.c:978 [<ffffffff81c5ccde>] avc_has_perm_noaudit security/selinux/avc.c:1114 [inline] [<ffffffff81c5ccde>] avc_has_perm+0x36e/0x4f0 security/selinux/avc.c:1148 [<ffffffff81c6e70c>] selinux_socket_create+0x1ac/0x410 security/selinux/hooks.c:4085 [<ffffffff81c56eb9>] security_socket_create+0x89/0xc0 security/security.c:1199 [<ffffffff82f29475>] __sock_create+0x65/0x5f0 net/socket.c:1145 [<ffffffff82f29c30>] sock_create net/socket.c:1230 [inline] [<ffffffff82f29c30>] SYSC_socket net/socket.c:1260 [inline] [<ffffffff82f29c30>] SyS_socket+0xf0/0x1b0 net/socket.c:1240 [<ffffffff838cc565>] entry_SYSCALL_64_fastpath+0x22/0x9e Code: 8c 02 00 00 48 8b 1b 41 be 01 00 00 00 48 85 db 74 46 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 18 41 83 c6 01 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e6 01 00 00 4c 3b 6b 18 0f 84 9e 00 00 00 48 RIP [<ffffffff81e77667>] lookup_object lib/debugobjects.c:120 [inline] RIP [<ffffffff81e77667>] debug_object_activate+0x1b7/0x480 lib/debugobjects.c:405 RSP <ffff8801bf687a10> ---[ end trace 40ab2e1a7d5fd77c ]---