[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.283182] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.425756] random: sshd: uninitialized urandom read (32 bytes read) [ 17.771976] random: sshd: uninitialized urandom read (32 bytes read) [ 18.630253] random: sshd: uninitialized urandom read (32 bytes read) [ 18.759381] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.17' (ECDSA) to the list of known hosts. [ 24.151156] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.349811] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.358283] IP: [] l2tp_session_free+0x11c/0x200 [ 24.364700] PGD 1c9279067 [ 24.367343] PUD 1c7c4d067 PMD 0 [ 24.370825] [ 24.372443] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.376917] Dumping ftrace buffer: [ 24.380425] (ftrace buffer empty) [ 24.384108] Modules linked in: [ 24.387432] CPU: 0 PID: 3795 Comm: syz-executor340 Not tainted 4.9.113-g9905591 #14 [ 24.395223] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.404587] task: ffff8801b96c9800 task.stack: ffff8801b71d8000 [ 24.410627] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.419475] RSP: 0018:ffff8801b71dfca0 EFLAGS: 00010246 [ 24.424897] RAX: dffffc0000000000 RBX: ffff8801ca8f5b80 RCX: 0000000000000000 [ 24.432140] RDX: 1ffff10039540a60 RSI: ffffffff836bcee1 RDI: ffff8801caa05300 [ 24.439387] RBP: ffff8801b71dfcc0 R08: ffff8801b96ca0e8 R09: 0000000000000000 [ 24.446630] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801caa05180 [ 24.453888] R13: ffff8801ca8f5b88 R14: 0000000000000000 R15: ffffffff83013be0 [ 24.461135] FS: 0000000001821880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.469422] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.475280] CR2: 0000000000000080 CR3: 00000001c1805000 CR4: 00000000001606f0 [ 24.482524] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.489776] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.497017] Stack: [ 24.499136] ffff8801d94b3300 ffff8801ca8f5b80 ffff8801d94b36d0 ffff8801d94b35d8 [ 24.507126] ffff8801b71dfce8 ffffffff836c47f2 ffff8801d94b3740 ffff8801d94b3300 [ 24.515130] ffffffff836c4720 ffff8801b71dfd20 ffffffff83021095 ffff8801d94b3740 [ 24.523122] Call Trace: [ 24.525686] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.532329] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.538629] [] __sk_destruct+0x55/0x590 [ 24.544240] [] ? sock_release+0x1c0/0x1c0 [ 24.550009] [] sk_destruct+0x63/0x80 [ 24.555349] [] __sk_free+0x4f/0x220 [ 24.560602] [] sk_free+0x2b/0x40 [ 24.565681] [] pppol2tp_release+0x239/0x2e0 [ 24.571637] [] sock_release+0x96/0x1c0 [ 24.577154] [] sock_close+0x16/0x20 [ 24.582408] [] __fput+0x263/0x700 [ 24.587486] [] ____fput+0x15/0x20 [ 24.592569] [] task_work_run+0x10c/0x180 [ 24.598294] [] exit_to_usermode_loop+0xfc/0x120 [ 24.604595] [] do_syscall_64+0x364/0x490 [ 24.610293] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.617413] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 55 1b ca fd 4c 89 ea 48 b8 00 [ 24.644544] RIP [] l2tp_session_free+0x11c/0x200 [ 24.651059] RSP [ 24.654658] CR2: 0000000000000080 [ 24.658291] ---[ end trace 59572e014487adc7 ]--- [ 24.663064] Kernel panic - not syncing: Fatal exception [ 24.668885] Dumping ftrace buffer: [ 24.672417] (ftrace buffer empty) [ 24.676103] Kernel Offset: disabled [ 24.679728] Rebooting in 86400 seconds..