[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.750412] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.306732] random: sshd: uninitialized urandom read (32 bytes read) [ 18.636278] random: sshd: uninitialized urandom read (32 bytes read) [ 19.568355] random: sshd: uninitialized urandom read (32 bytes read) [ 25.592329] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.203' (ECDSA) to the list of known hosts. [ 31.010379] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.227861] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.236108] IP: [] l2tp_session_free+0x11c/0x200 [ 31.242525] PGD 1c4ff8067 [ 31.245165] PUD 1c4dc6067 PMD 0 [ 31.248644] [ 31.250264] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.254736] Dumping ftrace buffer: [ 31.258248] (ftrace buffer empty) [ 31.261934] Modules linked in: [ 31.265223] CPU: 0 PID: 3801 Comm: syz-executor647 Not tainted 4.9.116-g52be322 #17 [ 31.273000] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.282327] task: ffff8801b8f76000 task.stack: ffff8801d91c8000 [ 31.288390] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.297241] RSP: 0018:ffff8801d91cfca0 EFLAGS: 00010246 [ 31.302668] RAX: dffffc0000000000 RBX: ffff8801c7c86a00 RCX: 0000000000000000 [ 31.309911] RDX: 1ffff10038f80fa0 RSI: ffffffff836be8f1 RDI: ffff8801c7c07d00 [ 31.317163] RBP: ffff8801d91cfcc0 R08: ffff8801b8f768e8 R09: 0000000000000000 [ 31.324405] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c7c07b80 [ 31.331647] R13: ffff8801c7c86a08 R14: 0000000000000000 R15: ffffffff83014be0 [ 31.338891] FS: 0000000002083880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 31.347089] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.352943] CR2: 0000000000000080 CR3: 00000001bc787000 CR4: 00000000001606f0 [ 31.360189] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 31.367441] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 31.374681] Stack: [ 31.376805] ffff8801b70a6e80 ffff8801c7c86a00 ffff8801b70a7250 ffff8801b70a7158 [ 31.384795] ffff8801d91cfce8 ffffffff836c6202 ffff8801b70a72c0 ffff8801b70a6e80 [ 31.392784] ffffffff836c6130 ffff8801d91cfd20 ffffffff83022095 ffff8801b70a72c0 [ 31.400849] Call Trace: [ 31.403421] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.410061] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.416353] [] __sk_destruct+0x55/0x590 [ 31.421961] [] ? sock_release+0x1c0/0x1c0 [ 31.427735] [] sk_destruct+0x63/0x80 [ 31.433069] [] __sk_free+0x4f/0x220 [ 31.438320] [] sk_free+0x2b/0x40 [ 31.443311] [] pppol2tp_release+0x239/0x2e0 [ 31.449256] [] sock_release+0x96/0x1c0 [ 31.454767] [] sock_close+0x16/0x20 [ 31.460030] [] __fput+0x263/0x700 [ 31.465108] [] ____fput+0x15/0x20 [ 31.470186] [] task_work_run+0x10c/0x180 [ 31.475878] [] exit_to_usermode_loop+0xfc/0x120 [ 31.482175] [] do_syscall_64+0x364/0x490 [ 31.487861] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.494756] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 31.521654] RIP [] l2tp_session_free+0x11c/0x200 [ 31.528153] RSP [ 31.531762] CR2: 0000000000000080 [ 31.535284] ---[ end trace 7773657769c3cf87 ]--- [ 31.540038] Kernel panic - not syncing: Fatal exception [ 31.545738] Dumping ftrace buffer: [ 31.549256] (ftrace buffer empty) [ 31.552941] Kernel Offset: disabled [ 31.556543] Rebooting in 86400 seconds..