================================================================== audit: type=1326 audit(1517585379.938:23): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=264 compat=0 ip=0x453299 code=0x7ffc0000 BUG: KASAN: use-after-free in l2tp_session_create+0x9aa/0xb80 net/l2tp/l2tp_core.c:1749 Read of size 4 at addr ffff8801b8ece668 by task syz-executor5/5419 audit: type=1326 audit(1517585379.938:24): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x7ffc0000 CPU: 0 PID: 5419 Comm: syz-executor5 Not tainted 4.15.0+ #292 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: audit: type=1326 audit(1517585379.939:25): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=257 compat=0 ip=0x453299 code=0x7ffc0000 __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 audit: type=1326 audit(1517585379.941:26): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x7ffc0000 audit: type=1326 audit(1517585379.942:27): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=54 compat=0 ip=0x453299 code=0x7ffc0000 print_address_description+0x73/0x250 mm/kasan/report.c:252 audit: type=1326 audit(1517585379.943:28): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 pid=5437 comm="syz-executor2" exe="/root/syz-executor2" sig=0 arch=c000003e syscall=202 compat=0 ip=0x453299 code=0x7ffc0000 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x25b/0x340 mm/kasan/report.c:409 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 l2tp_session_create+0x9aa/0xb80 net/l2tp/l2tp_core.c:1749 pppol2tp_connect+0xed7/0x1dd0 net/l2tp/l2tp_ppp.c:748 SYSC_connect+0x213/0x4a0 net/socket.c:1639 SyS_connect+0x24/0x30 net/socket.c:1620 entry_SYSCALL_64_fastpath+0x29/0xa0 RIP: 0033:0x453299 RSP: 002b:00007f33b4f88c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000453299 RDX: 0000000000000032 RSI: 0000000020e71000 RDI: 0000000000000014 RBP: 00000000000005da R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f7d10 R13: 00000000ffffffff R14: 00007f33b4f896d4 R15: 0000000000000000 Allocated by task 5419: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3606 kmalloc include/linux/slab.h:499 [inline] kzalloc include/linux/slab.h:688 [inline] l2tp_tunnel_create+0x5e1/0x17f0 net/l2tp/l2tp_core.c:1545 pppol2tp_connect+0x14b1/0x1dd0 net/l2tp/l2tp_ppp.c:707 SYSC_connect+0x213/0x4a0 net/socket.c:1639 SyS_connect+0x24/0x30 net/socket.c:1620 entry_SYSCALL_64_fastpath+0x29/0xa0 Freed by task 5433: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3484 [inline] kfree+0xd6/0x260 mm/slab.c:3799 __rcu_reclaim kernel/rcu/rcu.h:167 [inline] rcu_do_batch kernel/rcu/tree.c:2674 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline] rcu_process_callbacks+0xe94/0x17f0 kernel/rcu/tree.c:2917 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 The buggy address belongs to the object at ffff8801b8ece580 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 232 bytes inside of 512-byte region [ffff8801b8ece580, ffff8801b8ece780) The buggy address belongs to the page: page:ffffea0006e3b380 count:1 mapcount:0 mapping:ffff8801b8ece080 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801b8ece080 0000000000000000 0000000100000006 raw: ffffea0006da42e0 ffffea0006e3caa0 ffff8801db000940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801b8ece500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801b8ece580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801b8ece600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801b8ece680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b8ece700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================