[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.851283] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.285946] random: sshd: uninitialized urandom read (32 bytes read) [ 27.729201] random: sshd: uninitialized urandom read (32 bytes read) [ 28.242921] random: sshd: uninitialized urandom read (32 bytes read) [ 30.678228] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.55' (ECDSA) to the list of known hosts. [ 36.321421] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 36.517373] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 36.525591] IP: [] l2tp_session_free+0x11c/0x200 [ 36.532016] PGD 1cb240067 [ 36.534657] PUD 1cb241067 PMD 0 [ 36.538133] [ 36.539754] Oops: 0002 [#1] PREEMPT SMP KASAN [ 36.544223] Dumping ftrace buffer: [ 36.547732] (ftrace buffer empty) [ 36.551414] Modules linked in: [ 36.554703] CPU: 0 PID: 3808 Comm: syz-executor150 Not tainted 4.9.123-g8dd3fc2 #79 [ 36.562473] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.571806] task: ffff8801b85de000 task.stack: ffff8801d94e0000 [ 36.577835] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 36.586680] RSP: 0018:ffff8801d94e7ca0 EFLAGS: 00010246 [ 36.592106] RAX: dffffc0000000000 RBX: ffff8801b81b1900 RCX: 0000000000000000 [ 36.599348] RDX: 1ffff1003921bb00 RSI: ffffffff836c4991 RDI: ffff8801c90dd800 [ 36.606596] RBP: ffff8801d94e7cc0 R08: ffff8801b85de8e8 R09: 0000000000000000 [ 36.613934] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c90dd680 [ 36.621185] R13: ffff8801b81b1908 R14: 0000000000000000 R15: ffffffff8301abe0 [ 36.628432] FS: 0000000001481880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 36.636632] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.642488] CR2: 0000000000000080 CR3: 00000001c297d000 CR4: 00000000001606f0 [ 36.649732] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.656974] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.664215] Stack: [ 36.666343] ffff8801b6603300 ffff8801b81b1900 ffff8801b66036d0 ffff8801b66035d8 [ 36.674336] ffff8801d94e7ce8 ffffffff836cc2a2 ffff8801b6603740 ffff8801b6603300 [ 36.682434] ffffffff836cc1d0 ffff8801d94e7d20 ffffffff830280f5 ffff8801b6603740 [ 36.690485] Call Trace: [ 36.693055] [] pppol2tp_session_destruct+0xd2/0x110 [ 36.699711] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 36.706003] [] __sk_destruct+0x55/0x590 [ 36.711614] [] ? sock_release+0x1c0/0x1c0 [ 36.717399] [] sk_destruct+0x63/0x80 [ 36.722858] [] __sk_free+0x4f/0x220 [ 36.728117] [] sk_free+0x2b/0x40 [ 36.733111] [] pppol2tp_release+0x239/0x2e0 [ 36.739106] [] sock_release+0x96/0x1c0 [ 36.744628] [] sock_close+0x16/0x20 [ 36.749882] [] __fput+0x263/0x700 [ 36.755034] [] ____fput+0x15/0x20 [ 36.760121] [] task_work_run+0x10c/0x180 [ 36.765810] [] exit_to_usermode_loop+0xfc/0x120 [ 36.772107] [] do_syscall_64+0x364/0x490 [ 36.777792] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 36.784693] 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 [ 36.811589] RIP [] l2tp_session_free+0x11c/0x200 [ 36.818111] RSP [ 36.821710] CR2: 0000000000000080 [ 36.825605] ---[ end trace f91b0f07672d2d54 ]--- [ 36.830401] Kernel panic - not syncing: Fatal exception [ 36.836073] Dumping ftrace buffer: [ 36.839595] (ftrace buffer empty) [ 36.843281] Kernel Offset: disabled [ 36.846887] Rebooting in 86400 seconds..