random: sshd: uninitialized urandom read (32 bytes read, 120 bits of entropy available) random: sshd: uninitialized urandom read (32 bytes read, 122 bits of entropy available) random: nonblocking pool is initialized IPVS: Creating netns size=2552 id=1 ================================================================== BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 Read of size 4 at addr ffff8801cfecaf00 by task syz-executor790/3715 CPU: 1 PID: 3715 Comm: syz-executor790 Not tainted 4.4.131-g033c952 #37 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 35580966255d5a51 ffff8800b2c2fcc0 ffffffff81e0df8d ffffea00073fb280 ffff8801cfecaf00 0000000000000000 ffff8801cfecaf00 ffffffff82f18cb0 ffff8800b2c2fcf8 ffffffff8151520c ffff8801cfecaf00 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_address_description+0x6c/0x216 mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408 [] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428 [] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830 [] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509 [] sock_release+0x96/0x1c0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x235/0x6f0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10f/0x190 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:252 [] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 Allocated by task 3714: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616 [] __kmalloc+0x124/0x310 mm/slub.c:3613 [] kmalloc include/linux/slab.h:481 [inline] [] kzalloc include/linux/slab.h:620 [inline] [] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748 [] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725 [] SYSC_connect+0x1b8/0x300 net/socket.c:1557 [] SyS_connect+0x24/0x30 net/socket.c:1538 [] entry_SYSCALL_64_fastpath+0x22/0x9e Freed by task 3714: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589 [] slab_free_hook mm/slub.c:1383 [inline] [] slab_free_freelist_hook mm/slub.c:1405 [inline] [] slab_free mm/slub.c:2859 [inline] [] kfree+0xf4/0x310 mm/slub.c:3749 [] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676 [] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline] [] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279 [] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300 [] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1421 [] sk_common_release+0x6d/0x300 net/core/sock.c:2680 [] udp_lib_close+0x15/0x20 include/net/udp.h:190 [] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435 [] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424 [] sock_release+0x96/0x1c0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x235/0x6f0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10f/0x190 kernel/task_work.c:115 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0x13d/0x160 arch/x86/entry/common.c:252 [] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 The buggy address belongs to the object at ffff8801cfecaf00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801cfecaf00, ffff8801cfecb100) The buggy address belongs to the page: kasan: CONFIG_KASAN_INLINE enabled[ 32.317930] page:ffffea00073fb280 count:1 mapcount:-2146697203 mapping: (null) index:0x0 flags: 0xffff8801db219c40(active|reserved|private|private_2|swapcache|mappedtodisk|uncached) page dumped because: VM_BUG_ON_PAGE(PageSlab(page)) ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:464! invalid opcode: 0000 [#1] PREEMPT SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 3715 Comm: syz-executor790 Not tainted 4.4.131-g033c952 #37 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801cede4800 task.stack: ffff8800b2c28000 RIP: 0010:[] [] dump_page mm/debug.c:105 [inline] RIP: 0010:[] [] page_mapcount include/linux/mm.h:464 [inline] RIP: 0010:[] [] dump_page_badflags+0x57/0x70 mm/debug.c:85 RSP: 0018:ffff8800ade00030 EFLAGS: 00010093 RAX: 0000000000000000 RBX: ffffea00073fb280 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff81513249 RDI: ffff8801cede50dc RBP: ffff8800ade00060 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff858f74cb R12: 0000000000000000 R13: ffffffff83aa9be0 R14: ffff8801cfecaf00 R15: ffff8801cfecb100 FS: 00007f5607c04700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055c2d533a0f0 CR3: 00000001d199e000 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000000 ffffea00073fb280 0000000000000000 ffffffff83aa9be0 ffff8801cfecaf00 ffff8801cfecb100 ffff8800ade000a0 ffffffff8148c947 0000000000000000 ffffea00073fb280 0000000000000000 ffffffff83aa9be0 Call Trace: Code: 48 c1 ea 03 80 3c 02 00 75 23 48 8b 03 a8 80 0f 84 e6 67 08 00 e8 aa 48 ec ff 31 d2 48 c7 c6 e0 9b aa 83 48 89 df e8 a9 ff ff ff <0f> 0b 48 89 df e8 bf c6 06 00 eb d3 0f 1f 00 66 2e 0f 1f 84 00 RIP [] dump_page mm/debug.c:105 [inline] RIP [] page_mapcount include/linux/mm.h:464 [inline] RIP [] dump_page_badflags+0x57/0x70 mm/debug.c:85 RSP ---[ end trace ed8fdb85a78b74d5 ]---