[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.433151] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.552498] random: sshd: uninitialized urandom read (32 bytes read) [ 23.903795] random: sshd: uninitialized urandom read (32 bytes read) [ 24.414196] random: sshd: uninitialized urandom read (32 bytes read) [ 24.563757] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 30.068782] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.289604] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.297959] IP: [] l2tp_session_free+0x11c/0x200 [ 30.304382] PGD 1b742c067 [ 30.307031] PUD 1b7b6f067 PMD 0 [ 30.310550] [ 30.312172] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.316640] Dumping ftrace buffer: [ 30.320151] (ftrace buffer empty) [ 30.323840] Modules linked in: [ 30.327176] CPU: 1 PID: 3802 Comm: syz-executor429 Not tainted 4.9.122-g54068d6 #78 [ 30.334947] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.344282] task: ffff8801b7afb000 task.stack: ffff8801b58b8000 [ 30.350315] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.359173] RSP: 0018:ffff8801b58bfca0 EFLAGS: 00010246 [ 30.364606] RAX: dffffc0000000000 RBX: ffff8801b6092780 RCX: 0000000000000000 [ 30.371853] RDX: 1ffff10036bae0d0 RSI: ffffffff836c39a1 RDI: ffff8801b5d70680 [ 30.379098] RBP: ffff8801b58bfcc0 R08: ffff8801b7afb8e8 R09: 0000000000000000 [ 30.386344] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5d70500 [ 30.393684] R13: ffff8801b6092788 R14: 0000000000000000 R15: ffffffff83019be0 [ 30.400958] FS: 000000000190f880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 30.409263] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.415124] CR2: 0000000000000080 CR3: 00000001c519c000 CR4: 00000000001606f0 [ 30.422372] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.429617] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.436924] Stack: [ 30.439062] ffff8801b71f2a80 ffff8801b6092780 ffff8801b71f2e50 ffff8801b71f2d58 [ 30.447056] ffff8801b58bfce8 ffffffff836cb2b2 ffff8801b71f2ec0 ffff8801b71f2a80 [ 30.455056] ffffffff836cb1e0 ffff8801b58bfd20 ffffffff830270f5 ffff8801b71f2ec0 [ 30.463064] Call Trace: [ 30.465636] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.472282] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.478580] [] __sk_destruct+0x55/0x590 [ 30.484185] [] ? sock_release+0x1c0/0x1c0 [ 30.489966] [] sk_destruct+0x63/0x80 [ 30.495304] [] __sk_free+0x4f/0x220 [ 30.500556] [] sk_free+0x2b/0x40 [ 30.505556] [] pppol2tp_release+0x239/0x2e0 [ 30.511513] [] sock_release+0x96/0x1c0 [ 30.517030] [] sock_close+0x16/0x20 [ 30.522283] [] __fput+0x263/0x700 [ 30.527364] [] ____fput+0x15/0x20 [ 30.532445] [] task_work_run+0x10c/0x180 [ 30.538132] [] exit_to_usermode_loop+0xfc/0x120 [ 30.544428] [] do_syscall_64+0x364/0x490 [ 30.550245] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.557229] 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 [ 30.584170] RIP [] l2tp_session_free+0x11c/0x200 [ 30.590687] RSP [ 30.594289] CR2: 0000000000000080 [ 30.597839] ---[ end trace a74e5a8c967c8b5c ]--- [ 30.602609] Kernel panic - not syncing: Fatal exception [ 30.608284] Dumping ftrace buffer: [ 30.611800] (ftrace buffer empty) [ 30.615489] Kernel Offset: disabled [ 30.619087] Rebooting in 86400 seconds..