[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.094473] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.378985] random: sshd: uninitialized urandom read (32 bytes read) [ 19.830161] random: sshd: uninitialized urandom read (32 bytes read) [ 20.327380] random: sshd: uninitialized urandom read (32 bytes read) [ 20.467535] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.12' (ECDSA) to the list of known hosts. [ 25.957700] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.188895] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.197266] IP: [] l2tp_session_free+0x11c/0x200 [ 26.203794] PGD 1c94c6067 [ 26.206575] PUD 1b6e49067 PMD 0 [ 26.210108] [ 26.211741] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.216217] Dumping ftrace buffer: [ 26.219735] (ftrace buffer empty) [ 26.223592] Modules linked in: [ 26.227008] CPU: 1 PID: 3804 Comm: syz-executor499 Not tainted 4.9.123-g8dd3fc2 #27 [ 26.234780] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.244117] task: ffff8801b58d1800 task.stack: ffff8801d9838000 [ 26.250348] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.259644] RSP: 0018:ffff8801d983fca0 EFLAGS: 00010246 [ 26.265089] RAX: dffffc0000000000 RBX: ffff8801b5898000 RCX: 0000000000000000 [ 26.272503] RDX: 1ffff10036b130d0 RSI: ffffffff836c4991 RDI: ffff8801b5898680 [ 26.279886] RBP: ffff8801d983fcc0 R08: ffff8801b58d20e8 R09: 0000000000000000 [ 26.287241] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5898500 [ 26.294861] R13: ffff8801b5898008 R14: 0000000000000000 R15: ffffffff8301abe0 [ 26.302271] FS: 00000000020e8880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.310484] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.316470] CR2: 0000000000000080 CR3: 00000001c5e29000 CR4: 00000000001606f0 [ 26.323874] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.331130] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.338382] Stack: [ 26.340516] ffff8801b5785d80 ffff8801b5898000 ffff8801b5786150 ffff8801b5786058 [ 26.348681] ffff8801d983fce8 ffffffff836cc2a2 ffff8801b57861c0 ffff8801b5785d80 [ 26.356837] ffffffff836cc1d0 ffff8801d983fd20 ffffffff830280f5 ffff8801b57861c0 [ 26.364895] Call Trace: [ 26.367562] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.374509] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.381481] [] __sk_destruct+0x55/0x590 [ 26.387099] [] ? sock_release+0x1c0/0x1c0 [ 26.392993] [] sk_destruct+0x63/0x80 [ 26.398344] [] __sk_free+0x4f/0x220 [ 26.403608] [] sk_free+0x2b/0x40 [ 26.408609] [] pppol2tp_release+0x239/0x2e0 [ 26.414565] [] sock_release+0x96/0x1c0 [ 26.420097] [] sock_close+0x16/0x20 [ 26.425358] [] __fput+0x263/0x700 [ 26.430442] [] ____fput+0x15/0x20 [ 26.435531] [] task_work_run+0x10c/0x180 [ 26.441226] [] exit_to_usermode_loop+0xfc/0x120 [ 26.447529] [] do_syscall_64+0x364/0x490 [ 26.453223] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.460129] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 26.488397] RIP [] l2tp_session_free+0x11c/0x200 [ 26.494919] RSP [ 26.498526] CR2: 0000000000000080 [ 26.502118] ---[ end trace 3c15e0bcf3a22428 ]--- [ 26.506877] Kernel panic - not syncing: Fatal exception [ 26.512682] Dumping ftrace buffer: [ 26.516217] (ftrace buffer empty) [ 26.519909] Kernel Offset: disabled [ 26.523520] Rebooting in 86400 seconds..