[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.043384] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [ 13.926295] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.486168] random: sshd: uninitialized urandom read (32 bytes read) [ 15.420603] random: sshd: uninitialized urandom read (32 bytes read) [ 15.546613] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.30' (ECDSA) to the list of known hosts. [ 21.006084] random: sshd: uninitialized urandom read (32 bytes read) 2018/07/18 04:56:49 parsed 1 programs [ 22.739253] random: cc1: uninitialized urandom read (8 bytes read) 2018/07/18 04:56:51 executed programs: 0 [ 23.735290] IPVS: Creating netns size=2536 id=1 [ 24.401353] ================================================================== [ 24.408747] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 24.416003] Read of size 4 at addr ffff8801c3ee1b80 by task syz-executor0/3850 [ 24.423339] [ 24.424947] CPU: 1 PID: 3850 Comm: syz-executor0 Not tainted 4.9.112-gf540ce0 #12 [ 24.432563] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.441899] ffff8801d97ffca0 ffffffff81eb3249 ffffea00070fb800 ffff8801c3ee1b80 [ 24.449916] 0000000000000000 ffff8801c3ee1b80 ffffffff83013be0 ffff8801d97ffcd8 [ 24.458184] ffffffff81567bd9 ffff8801c3ee1b80 0000000000000004 0000000000000000 [ 24.466171] Call Trace: [ 24.468737] [<ffffffff81eb3249>] dump_stack+0xc1/0x128 [ 24.474083] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 24.479857] [<ffffffff81567bd9>] print_address_description+0x6c/0x234 [ 24.486507] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 24.492297] [<ffffffff81567fe3>] kasan_report.cold.6+0x242/0x2fe [ 24.498519] [<ffffffff836bbc14>] ? l2tp_session_queue_purge+0xf4/0x100 [ 24.505255] [<ffffffff8153bc14>] __asan_report_load4_noabort+0x14/0x20 [ 24.511982] [<ffffffff836bbc14>] l2tp_session_queue_purge+0xf4/0x100 [ 24.518538] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 24.524325] [<ffffffff836c789b>] pppol2tp_release+0x1fb/0x2e0 [ 24.530283] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 24.535816] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 24.541085] [<ffffffff815782e3>] __fput+0x263/0x700 [ 24.546183] [<ffffffff81578805>] ____fput+0x15/0x20 [ 24.551263] [<ffffffff8119839c>] task_work_run+0x10c/0x180 [ 24.556952] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 24.563249] [<ffffffff81007073>] do_fast_syscall_32+0x5c3/0x870 [ 24.569388] [<ffffffff81003036>] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 24.576037] [<ffffffff839fb650>] entry_SYSENTER_compat+0x90/0xa2 [ 24.582242] [ 24.583846] Allocated by task 3850: [ 24.587450] save_stack_trace+0x16/0x20 [ 24.591397] save_stack+0x43/0xd0 [ 24.594822] kasan_kmalloc+0xc7/0xe0 [ 24.598514] __kmalloc+0x11d/0x300 [ 24.602035] l2tp_session_create+0x38/0x16f0 [ 24.606426] pppol2tp_connect+0x10d7/0x18f0 [ 24.610738] SYSC_connect+0x1b8/0x300 [ 24.614522] SyS_connect+0x24/0x30 [ 24.618054] do_fast_syscall_32+0x2f7/0x870 [ 24.622376] entry_SYSENTER_compat+0x90/0xa2 [ 24.626758] [ 24.628359] Freed by task 3848: [ 24.631615] save_stack_trace+0x16/0x20 [ 24.635569] save_stack+0x43/0xd0 [ 24.638996] kasan_slab_free+0x72/0xc0 [ 24.642865] kfree+0xfb/0x310 [ 24.645968] l2tp_session_free+0x166/0x200 [ 24.650187] l2tp_tunnel_closeall+0x284/0x350 [ 24.654659] l2tp_udp_encap_destroy+0x87/0xe0 [ 24.659139] udp_destroy_sock+0x118/0x1a0 [ 24.663273] sk_common_release+0x6d/0x300 [ 24.667402] udp_lib_close+0x15/0x20 [ 24.671101] inet_release+0xff/0x1d0 [ 24.674798] sock_release+0x96/0x1c0 [ 24.678485] sock_close+0x16/0x20 [ 24.681911] __fput+0x263/0x700 [ 24.685164] ____fput+0x15/0x20 [ 24.688425] task_work_run+0x10c/0x180 [ 24.692293] exit_to_usermode_loop+0xfc/0x120 [ 24.696768] do_fast_syscall_32+0x5c3/0x870 [ 24.701073] entry_SYSENTER_compat+0x90/0xa2 [ 24.705451] [ 24.707057] The buggy address belongs to the object at ffff8801c3ee1b80 [ 24.707057] which belongs to the cache kmalloc-512 of size 512 [ 24.719692] The buggy address is located 0 bytes inside of [ 24.719692] 512-byte region [ffff8801c3ee1b80, ffff8801c3ee1d80) [ 24.731375] The buggy address belongs to the page: [ 24.736297] page:ffffea00070fb800 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 24.746481] flags: 0x8000000000004080(slab|head) [ 24.751215] page dumped because: kasan: bad access detected [ 24.756923] [ 24.758525] Memory state around the buggy address: [ 24.763521] ffff8801c3ee1a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.770851] ffff8801c3ee1b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 24.778196] >ffff8801c3ee1b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.785537] ^ [ 24.788880] ffff8801c3ee1c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.796220] ffff8801c3ee1c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 24.803552] ================================================================== [ 24.810891] Disabling lock debugging due to kernel taint [ 24.816812] Kernel panic - not syncing: panic_on_warn set ... [ 24.816812] [ 24.824175] CPU: 1 PID: 3850 Comm: syz-executor0 Tainted: G B 4.9.112-gf540ce0 #12 [ 24.832996] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.842336] ffff8801d97ffc00 ffffffff81eb3249 ffffffff843c77c7 00000000ffffffff [ 24.850329] 0000000000000000 0000000000000001 ffffffff83013be0 ffff8801d97ffcc0 [ 24.858354] ffffffff81421a55 0000000041b58ab3 ffffffff843baee0 ffffffff81421896 [ 24.866360] Call Trace: [ 24.868927] [<ffffffff81eb3249>] dump_stack+0xc1/0x128 [ 24.874267] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 24.880562] [<ffffffff81421a55>] panic+0x1bf/0x3bc [ 24.885553] [<ffffffff81421896>] ? add_taint.cold.6+0x16/0x16 [ 24.891496] [<ffffffff81003066>] ? ___preempt_schedule+0x16/0x18 [ 24.897700] [<ffffffff81567af6>] kasan_end_report+0x47/0x4f [ 24.903473] [<ffffffff81567e17>] kasan_report.cold.6+0x76/0x2fe [ 24.909602] [<ffffffff836bbc14>] ? l2tp_session_queue_purge+0xf4/0x100 [ 24.916331] [<ffffffff8153bc14>] __asan_report_load4_noabort+0x14/0x20 [ 24.923070] [<ffffffff836bbc14>] l2tp_session_queue_purge+0xf4/0x100 [ 24.929630] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 24.935424] [<ffffffff836c789b>] pppol2tp_release+0x1fb/0x2e0 [ 24.941872] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 24.947387] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 24.952656] [<ffffffff815782e3>] __fput+0x263/0x700 [ 24.957739] [<ffffffff81578805>] ____fput+0x15/0x20 [ 24.963110] [<ffffffff8119839c>] task_work_run+0x10c/0x180 [ 24.968798] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 24.975095] [<ffffffff81007073>] do_fast_syscall_32+0x5c3/0x870 [ 24.981220] [<ffffffff81003036>] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 24.987866] [<ffffffff839fb650>] entry_SYSENTER_compat+0x90/0xa2 [ 24.994618] Dumping ftrace buffer: [ 24.998140] (ftrace buffer empty) [ 25.001830] Kernel Offset: disabled [ 25.005429] Rebooting in 86400 seconds..