[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.511194] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.585043] random: sshd: uninitialized urandom read (32 bytes read) [ 21.775500] random: sshd: uninitialized urandom read (32 bytes read) [ 22.285315] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.33' (ECDSA) to the list of known hosts. [ 28.100314] urandom_read: 1 callbacks suppressed [ 28.100317] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.305933] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.314179] IP: [] l2tp_session_free+0x11c/0x200 [ 28.320741] PGD 1c502f067 [ 28.323387] PUD 1c5082067 PMD 0 [ 28.326872] [ 28.328496] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.332965] Dumping ftrace buffer: [ 28.336480] (ftrace buffer empty) [ 28.340204] Modules linked in: [ 28.343499] CPU: 0 PID: 3769 Comm: syz-executor027 Not tainted 4.9.123-g7fa8c15 #80 [ 28.351265] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.360595] task: ffff8801bbf06000 task.stack: ffff8801bb158000 [ 28.366627] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.375773] RSP: 0018:ffff8801bb15fc98 EFLAGS: 00010246 [ 28.381203] RAX: dffffc0000000000 RBX: ffff8801bc31f400 RCX: 0000000000000000 [ 28.388453] RDX: 1ffff10037863030 RSI: ffffffff836c4a91 RDI: ffff8801bc318180 [ 28.395698] RBP: ffff8801bb15fcb8 R08: ffff8801bbf068e8 R09: 0000000000000000 [ 28.402948] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bc318000 [ 28.410195] R13: ffff8801bc31f408 R14: 0000000000000000 R15: 0000000000000000 [ 28.417484] FS: 00000000006eb880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.425691] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.431547] CR2: 0000000000000080 CR3: 00000001c68b9000 CR4: 00000000001606f0 [ 28.438887] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.446258] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.453503] Stack: [ 28.455629] ffff8801d7138000 ffff8801bc31f400 ffff8801d71383d0 ffff8801d71382d8 [ 28.463700] ffff8801bb15fce0 ffffffff836cc3a2 ffff8801d7138440 ffff8801d7138000 [ 28.471757] ffffffff836cc2d0 ffff8801bb15fd18 ffffffff830281f5 ffff8801d7138440 [ 28.479775] Call Trace: [ 28.482345] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.488996] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.495359] [] __sk_destruct+0x55/0x590 [ 28.500973] [] sk_destruct+0x63/0x80 [ 28.506312] [] __sk_free+0x4f/0x220 [ 28.511624] [] sk_free+0x2b/0x40 [ 28.516623] [] pppol2tp_release+0x239/0x2e0 [ 28.522570] [] __sock_release+0xd7/0x260 [ 28.528256] [] ? __sock_release+0x260/0x260 [ 28.534202] [] sock_close+0x19/0x20 [ 28.539461] [] __fput+0x263/0x700 [ 28.544539] [] ____fput+0x15/0x20 [ 28.549628] [] task_work_run+0x10c/0x180 [ 28.555315] [] exit_to_usermode_loop+0xfc/0x120 [ 28.561607] [] do_syscall_64+0x364/0x490 [ 28.567298] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.574296] 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 c2 c9 fd 4c 89 ea 48 b8 00 [ 28.601629] RIP [] l2tp_session_free+0x11c/0x200 [ 28.608141] RSP [ 28.611738] CR2: 0000000000000080 [ 28.615585] ---[ end trace 92a58e70eccf021a ]--- [ 28.620344] Kernel panic - not syncing: Fatal exception [ 28.626124] Dumping ftrace buffer: [ 28.629642] (ftrace buffer empty) [ 28.633323] Kernel Offset: disabled [ 28.636923] Rebooting in 86400 seconds..