random: sshd: uninitialized urandom read (32 bytes read, 38 bits of entropy available)
random: sshd: uninitialized urandom read (32 bytes read, 38 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 ffff8801d8c24000 by task syz-executor821/3854

CPU: 0 PID: 3854 Comm: syz-executor821 Not tainted 4.4.138-g07c0138 #62
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 23cfd72a4ec0bf22 ffff8801c670fcc0 ffffffff81e0ed0d
 ffffea0007630900 ffff8801d8c24000 0000000000000000 ffff8801d8c24000
 ffffffff82f1a2b0 ffff8801c670fcf8 ffffffff81515a16 ffff8801d8c24000
Call Trace:
 [<ffffffff81e0ed0d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81e0ed0d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81515a16>] print_address_description+0x6c/0x216 mm/kasan/report.c:252
 [<ffffffff81515d35>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81515d35>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814f9804>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff8359ad34>] l2tp_session_queue_purge+0xf4/0x100 net/l2tp/l2tp_core.c:830
 [<ffffffff835a786f>] pppol2tp_release+0x1ff/0x310 net/l2tp/l2tp_ppp.c:509
 [<ffffffff82f1a186>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a2c6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522e05>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81523345>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bd7f>] 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:252
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838c28b5>] int_ret_from_sys_call+0x25/0xa3

Allocated by task 3853:
 [<ffffffff81033e46>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f88d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8bb7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8bb7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f52d4>] __kmalloc+0x124/0x310 mm/slub.c:3613
 [<ffffffff835a0179>] kmalloc include/linux/slab.h:481 [inline]
 [<ffffffff835a0179>] kzalloc include/linux/slab.h:620 [inline]
 [<ffffffff835a0179>] l2tp_session_create+0x39/0x1030 net/l2tp/l2tp_core.c:1748
 [<ffffffff835a4e80>] pppol2tp_connect+0x10f0/0x1910 net/l2tp/l2tp_ppp.c:725
 [<ffffffff82f1eba8>] SYSC_connect+0x1b8/0x300 net/socket.c:1557
 [<ffffffff82f214e4>] SyS_connect+0x24/0x30 net/socket.c:1538
 [<ffffffff838c2725>] entry_SYSCALL_64_fastpath+0x22/0x9e

Freed by task 3853:
 [<ffffffff81033e46>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f88d3>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f9202>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f9202>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589
 [<ffffffff814f6704>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff814f6704>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff814f6704>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff814f6704>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff8359d0e0>] l2tp_session_free+0x170/0x200 net/l2tp/l2tp_core.c:1676
 [<ffffffff8359f499>] l2tp_session_dec_refcount_1 net/l2tp/l2tp_core.h:293 [inline]
 [<ffffffff8359f499>] l2tp_tunnel_closeall+0x2b9/0x350 net/l2tp/l2tp_core.c:1279
 [<ffffffff8359ffab>] l2tp_udp_encap_destroy+0x8b/0xf0 net/l2tp/l2tp_core.c:1300
 [<ffffffff832cbe58>] udp_destroy_sock+0x118/0x1a0 net/ipv4/udp.c:2056
 [<ffffffff82f2fa5d>] sk_common_release+0x6d/0x300 net/core/sock.c:2680
 [<ffffffff832c9e65>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff832f8bef>] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff82f1a186>] sock_release+0x96/0x1c0 net/socket.c:586
 [<ffffffff82f1a2c6>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522e05>] __fput+0x235/0x6f0 fs/file_table.c:208
 [<ffffffff81523345>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bd7f>] 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:252
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348
 [<ffffffff838c28b5>] int_ret_from_sys_call+0x25/0xa3

The buggy address belongs to the object at ffff8801d8c24000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff8801d8c24000, ffff8801d8c24200)
The buggy address belongs to the page:
PANIC: double fault, error_code: 0x0
CPU: 0 PID: 3854 Comm: syz-executor821 Not tainted 4.4.138-g07c0138 #62
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8db8000 task.stack: ffff8801c6708000
RIP: 0010:[<ffffffff8148cf32>]  [<ffffffff8148cf32>] dump_page_badflags+0x12/0x70 mm/debug.c:84
RSP: 0018:ffff880100000000  EFLAGS: 00010046
RAX: ffff8801d8db8000 RBX: ffffea0007630900 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff83aa9de0 RDI: ffffea0007630900
RBP: ffff880100000020 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff858ed0f4 R12: 0000000000000000
R13: ffffffff83aa9de0 R14: ffff8801d8c24000 R15: ffff8801d8c24200
FS:  00007f87bf1cd700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8800fffffff8 CR3: 00000001c9950000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:

Call Trace:
 <UNK> 
Code: 42 9f 84 5b 5d c3 48 89 df e8 fb c8 06 00 eb dd 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41 56 41 55 49 89 f5 41 54 49 89 d4 <53> 48 89 fb 48 83 ec 08 e8 71 45 ec ff 48 89 da 48 b8 00 00 00