[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.341814] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.091520] random: sshd: uninitialized urandom read (32 bytes read) [ 15.302244] random: sshd: uninitialized urandom read (32 bytes read) [ 15.806042] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.42' (ECDSA) to the list of known hosts. [ 21.711743] urandom_read: 1 callbacks suppressed [ 21.711747] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.913728] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.921960] IP: [] l2tp_session_free+0x11c/0x200 [ 21.928415] PGD 1b7f01067 [ 21.931060] PUD 1ca58c067 PMD 0 [ 21.934540] [ 21.936162] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.940630] Dumping ftrace buffer: [ 21.944146] (ftrace buffer empty) [ 21.947831] Modules linked in: [ 21.951120] CPU: 1 PID: 3793 Comm: syz-executor083 Not tainted 4.9.122-g54068d6 #78 [ 21.958885] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.968214] task: ffff8801b7726000 task.stack: ffff8801b5fa8000 [ 21.974247] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.983096] RSP: 0018:ffff8801b5fafca0 EFLAGS: 00010246 [ 21.988519] RAX: dffffc0000000000 RBX: ffff8801b5ed9680 RCX: 0000000000000000 [ 21.995765] RDX: 1ffff10036b9c300 RSI: ffffffff836c39a1 RDI: ffff8801b5ce1800 [ 22.003029] RBP: ffff8801b5fafcc0 R08: ffff8801b77268e8 R09: 0000000000000000 [ 22.010291] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5ce1680 [ 22.017537] R13: ffff8801b5ed9688 R14: 0000000000000000 R15: ffffffff83019be0 [ 22.024784] FS: 00000000020c0880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.033003] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.038861] CR2: 0000000000000080 CR3: 00000001cb18e000 CR4: 00000000001606f0 [ 22.046107] Stack: [ 22.048292] ffff8801b5cf3b80 ffff8801b5ed9680 ffff8801b5cf3f50 ffff8801b5cf3e58 [ 22.056292] ffff8801b5fafce8 ffffffff836cb2b2 ffff8801b5cf3fc0 ffff8801b5cf3b80 [ 22.064286] ffffffff836cb1e0 ffff8801b5fafd20 ffffffff830270f5 ffff8801b5cf3fc0 [ 22.072287] Call Trace: [ 22.074855] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.081496] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.087792] [] __sk_destruct+0x55/0x590 [ 22.093390] [] ? sock_release+0x1c0/0x1c0 [ 22.099164] [] sk_destruct+0x63/0x80 [ 22.104506] [] __sk_free+0x4f/0x220 [ 22.109758] [] sk_free+0x2b/0x40 [ 22.114751] [] pppol2tp_release+0x239/0x2e0 [ 22.120698] [] sock_release+0x96/0x1c0 [ 22.126230] [] sock_close+0x16/0x20 [ 22.131487] [] __fput+0x263/0x700 [ 22.136568] [] ____fput+0x15/0x20 [ 22.141647] [] task_work_run+0x10c/0x180 [ 22.147352] [] exit_to_usermode_loop+0xfc/0x120 [ 22.153652] [] do_syscall_64+0x364/0x490 [ 22.159343] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.166241] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 22.193161] RIP [] l2tp_session_free+0x11c/0x200 [ 22.199674] RSP [ 22.203274] CR2: 0000000000000080 [ 22.207038] ---[ end trace 4b8b8d59fc02d1c6 ]--- [ 22.211794] Kernel panic - not syncing: Fatal exception [ 22.217444] Dumping ftrace buffer: [ 22.220976] (ftrace buffer empty) [ 22.224660] Kernel Offset: disabled [ 22.228262] Rebooting in 86400 seconds..