[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.002600] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.434880] random: sshd: uninitialized urandom read (32 bytes read) [ 27.879674] random: sshd: uninitialized urandom read (32 bytes read) [ 28.300351] random: sshd: uninitialized urandom read (32 bytes read) [ 31.935031] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.194' (ECDSA) to the list of known hosts. [ 37.326313] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 37.523230] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 37.531490] IP: [] l2tp_session_free+0x11c/0x200 [ 37.537908] PGD 1c071e067 [ 37.540546] PUD 1c07b8067 PMD 0 [ 37.544035] [ 37.545672] Oops: 0002 [#1] PREEMPT SMP KASAN [ 37.550140] Dumping ftrace buffer: [ 37.553653] (ftrace buffer empty) [ 37.557339] Modules linked in: [ 37.560626] CPU: 1 PID: 3781 Comm: syz-executor844 Not tainted 4.9.117-g8b21e85 #19 [ 37.568389] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.577714] task: ffff8801bc884800 task.stack: ffff8801bae08000 [ 37.583741] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 37.592590] RSP: 0018:ffff8801bae0fca0 EFLAGS: 00010246 [ 37.598024] RAX: dffffc0000000000 RBX: ffff8801badc1680 RCX: 0000000000000000 [ 37.605269] RDX: 1ffff10037612610 RSI: ffffffff836bf8f1 RDI: ffff8801bb093080 [ 37.612529] RBP: ffff8801bae0fcc0 R08: ffff8801bc8850e8 R09: 0000000000000000 [ 37.619778] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bb092f00 [ 37.627024] R13: ffff8801badc1688 R14: 0000000000000000 R15: ffffffff83015be0 [ 37.634272] FS: 0000000001a45880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 37.642473] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.648327] CR2: 0000000000000080 CR3: 00000001c8805000 CR4: 00000000001606f0 [ 37.655588] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 37.662831] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 37.670073] Stack: [ 37.672195] ffff8801bf716600 ffff8801badc1680 ffff8801bf7169d0 ffff8801bf7168d8 [ 37.680188] ffff8801bae0fce8 ffffffff836c7202 ffff8801bf716a40 ffff8801bf716600 [ 37.688188] ffffffff836c7130 ffff8801bae0fd20 ffffffff83023095 ffff8801bf716a40 [ 37.696168] Call Trace: [ 37.698737] [] pppol2tp_session_destruct+0xd2/0x110 [ 37.705378] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 37.711675] [] __sk_destruct+0x55/0x590 [ 37.717276] [] ? sock_release+0x1c0/0x1c0 [ 37.723046] [] sk_destruct+0x63/0x80 [ 37.728385] [] __sk_free+0x4f/0x220 [ 37.733691] [] sk_free+0x2b/0x40 [ 37.738681] [] pppol2tp_release+0x239/0x2e0 [ 37.744625] [] sock_release+0x96/0x1c0 [ 37.750133] [] sock_close+0x16/0x20 [ 37.755386] [] __fput+0x263/0x700 [ 37.760462] [] ____fput+0x15/0x20 [ 37.765545] [] task_work_run+0x10c/0x180 [ 37.771230] [] exit_to_usermode_loop+0xfc/0x120 [ 37.777523] [] do_syscall_64+0x364/0x490 [ 37.783220] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 37.790117] 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 f1 c9 fd 4c 89 ea 48 b8 00 [ 37.816872] RIP [] l2tp_session_free+0x11c/0x200 [ 37.823367] RSP [ 37.826965] CR2: 0000000000000080 [ 37.830529] ---[ end trace c9117e7478aedba4 ]--- [ 37.835285] Kernel panic - not syncing: Fatal exception [ 37.840904] Dumping ftrace buffer: [ 37.844421] (ftrace buffer empty) [ 37.848110] Kernel Offset: disabled [ 37.851714] Rebooting in 86400 seconds..