audit: type=1400 audit(1572725972.691:39): avc: denied { map } for pid=6842 comm="syz-executor.0" path=2F6D656D66643A73656375726974792E73656C696E7578202864656C6574656429 dev="tmpfs" ino=24488 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:tmpfs_t:s0 tclass=file permissive=1 ================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf2/0x100 net/l2tp/l2tp_core.c:874 Read of size 4 at addr ffff88808f830780 by task syz-executor.0/8281 CPU: 0 PID: 8281 Comm: syz-executor.0 Not tainted 4.14.151 #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+0x138/0x197 lib/dump_stack.c:53 print_address_description.cold+0x7c/0x1dc 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+0xa9/0x2af mm/kasan/report.c:393 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 l2tp_session_queue_purge+0xf2/0x100 net/l2tp/l2tp_core.c:874 l2tp_tunnel_closeall+0x20c/0x380 net/l2tp/l2tp_core.c:1337 l2tp_udp_encap_destroy+0x99/0x100 net/l2tp/l2tp_core.c:1366 udpv6_destroy_sock+0xb3/0xd0 net/ipv6/udp.c:1444 sk_common_release+0x6b/0x310 net/core/sock.c:2989 udp_lib_close+0x16/0x20 include/net/udp.h:203 inet_release+0xec/0x1c0 net/ipv4/af_inet.c:425 inet6_release+0x53/0x80 net/ipv6/af_inet6.c:450 __sock_release+0xce/0x2b0 net/socket.c:602 sock_close+0x1b/0x30 net/socket.c:1139 __fput+0x275/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x114/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1da/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+0x4bc/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x413ae1 RSP: 002b:00007ffcac2ca090 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000413ae1 RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000005 RBP: 0000000000000000 R08: 0000000000760760 R09: ffffffffffffffff R10: 00007ffcac2ca160 R11: 0000000000000293 R12: 000000000075bf20 R13: 0000000000000003 R14: 0000000000760768 R15: 000000000075bf2c Allocated by task 8282: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15d/0x7a0 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:661 [inline] l2tp_session_create+0x38/0x1600 net/l2tp/l2tp_core.c:1791 pppol2tp_connect+0x11bf/0x18b0 net/l2tp/l2tp_ppp.c:721 SYSC_connect+0x1f6/0x2d0 net/socket.c:1655 SyS_connect+0x24/0x30 net/socket.c:1636 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 8282: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x45/0xd0 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+0xcc/0x270 mm/slab.c:3815 l2tp_session_free+0x176/0x210 net/l2tp/l2tp_core.c:1714 l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:300 [inline] pppol2tp_session_destruct+0xd8/0x110 net/l2tp/l2tp_ppp.c:460 __sk_destruct+0x4f/0x580 net/core/sock.c:1556 sk_destruct+0xa4/0xd0 net/core/sock.c:1596 __sk_free+0x54/0x230 net/core/sock.c:1604 sk_free+0x35/0x40 net/core/sock.c:1615 sock_put include/net/sock.h:1653 [inline] pppol2tp_release+0x244/0x300 net/l2tp/l2tp_ppp.c:501 __sock_release+0xce/0x2b0 net/socket.c:602 sock_close+0x1b/0x30 net/socket.c:1139 __fput+0x275/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x114/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1da/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+0x4bc/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 The buggy address belongs to the object at ffff88808f830780 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff88808f830780, ffff88808f830980) The buggy address belongs to the page: page:ffffea00023e0c00 count:1 mapcount:0 mapping:ffff88808f830000 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffff88808f830000 0000000000000000 0000000100000006 raw: ffffea00023eece0 ffffea00023ebda0 ffff8880aa800940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808f830680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808f830700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88808f830780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808f830800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808f830880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================