[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.754897] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.847988] random: sshd: uninitialized urandom read (32 bytes read) [ 18.131015] random: sshd: uninitialized urandom read (32 bytes read) [ 19.019112] random: sshd: uninitialized urandom read (32 bytes read) [ 19.144748] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.35' (ECDSA) to the list of known hosts. [ 24.513678] random: sshd: uninitialized urandom read (32 bytes read) 2018/07/31 10:38:58 parsed 1 programs [ 26.214759] random: cc1: uninitialized urandom read (8 bytes read) 2018/07/31 10:39:00 executed programs: 0 [ 27.104883] IPVS: Creating netns size=2536 id=1 [ 27.224613] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 27.235686] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 27.276661] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 27.287609] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 27.328973] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 27.340230] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 27.351434] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 27.372001] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 27.830150] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 27.854175] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 27.860331] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 27.867987] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 28.196711] ================================================================== [ 28.204121] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 28.211375] Read of size 4 at addr ffff8801d846ac80 by task syz-executor0/4189 [ 28.218708] [ 28.220316] CPU: 0 PID: 4189 Comm: syz-executor0 Not tainted 4.9.113-g8956c50 #19 [ 28.227910] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.237242] ffff8801d4fd7ca0 ffffffff81eb32a9 ffffea0007611a80 ffff8801d846ac80 [ 28.245238] 0000000000000000 ffff8801d846ac80 ffffffff83013be0 ffff8801d4fd7cd8 [ 28.253229] ffffffff81567bd9 ffff8801d846ac80 0000000000000004 0000000000000000 [ 28.261216] Call Trace: [ 28.263781] [] dump_stack+0xc1/0x128 [ 28.269124] [] ? sock_release+0x1c0/0x1c0 [ 28.274897] [] print_address_description+0x6c/0x234 [ 28.281539] [] ? sock_release+0x1c0/0x1c0 [ 28.287314] [] kasan_report.cold.6+0x242/0x2fe [ 28.293526] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 28.300271] [] __asan_report_load4_noabort+0x14/0x20 [ 28.307010] [] l2tp_session_queue_purge+0xf4/0x100 [ 28.313572] [] ? sock_release+0x1c0/0x1c0 [ 28.319349] [] pppol2tp_release+0x1fb/0x2e0 [ 28.325301] [] sock_release+0x96/0x1c0 [ 28.330814] [] sock_close+0x16/0x20 [ 28.336082] [] __fput+0x263/0x700 [ 28.341159] [] ____fput+0x15/0x20 [ 28.346239] [] task_work_run+0x10c/0x180 [ 28.351926] [] exit_to_usermode_loop+0xfc/0x120 [ 28.358218] [] do_fast_syscall_32+0x5c3/0x870 [ 28.364623] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 28.371269] [] entry_SYSENTER_compat+0x90/0xa2 [ 28.377473] [ 28.379085] Allocated by task 4188: [ 28.382690] save_stack_trace+0x16/0x20 [ 28.386642] save_stack+0x43/0xd0 [ 28.390077] kasan_kmalloc+0xc7/0xe0 [ 28.393765] __kmalloc+0x11d/0x300 [ 28.397279] l2tp_session_create+0x38/0x16f0 [ 28.401661] pppol2tp_connect+0x10d7/0x18f0 [ 28.405968] SYSC_connect+0x1b8/0x300 [ 28.409742] SyS_connect+0x24/0x30 [ 28.413260] do_fast_syscall_32+0x2f7/0x870 [ 28.417558] entry_SYSENTER_compat+0x90/0xa2 [ 28.421937] [ 28.423540] Freed by task 4188: [ 28.426807] save_stack_trace+0x16/0x20 [ 28.430754] save_stack+0x43/0xd0 [ 28.434179] kasan_slab_free+0x72/0xc0 [ 28.438042] kfree+0xfb/0x310 [ 28.441121] l2tp_session_free+0x166/0x200 [ 28.445330] l2tp_tunnel_closeall+0x284/0x350 [ 28.449798] l2tp_udp_encap_destroy+0x87/0xe0 [ 28.454267] udpv6_destroy_sock+0xb1/0xd0 [ 28.458401] sk_common_release+0x6d/0x300 [ 28.462522] udp_lib_close+0x15/0x20 [ 28.466212] inet_release+0xff/0x1d0 [ 28.469900] inet6_release+0x50/0x70 [ 28.473588] sock_release+0x96/0x1c0 [ 28.477276] sock_close+0x16/0x20 [ 28.480713] __fput+0x263/0x700 [ 28.483966] ____fput+0x15/0x20 [ 28.487223] task_work_run+0x10c/0x180 [ 28.491097] exit_to_usermode_loop+0xfc/0x120 [ 28.495565] do_fast_syscall_32+0x5c3/0x870 [ 28.499861] entry_SYSENTER_compat+0x90/0xa2 [ 28.504240] [ 28.505843] The buggy address belongs to the object at ffff8801d846ac80 [ 28.505843] which belongs to the cache kmalloc-512 of size 512 [ 28.518474] The buggy address is located 0 bytes inside of [ 28.518474] 512-byte region [ffff8801d846ac80, ffff8801d846ae80) [ 28.530144] The buggy address belongs to the page: [ 28.535048] page:ffffea0007611a80 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 28.545226] flags: 0x8000000000004080(slab|head) [ 28.549954] page dumped because: kasan: bad access detected [ 28.555633] [ 28.557233] Memory state around the buggy address: [ 28.562136] ffff8801d846ab80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc [ 28.569469] ffff8801d846ac00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 28.576801] >ffff8801d846ac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.584136] ^ [ 28.587478] ffff8801d846ad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.594816] ffff8801d846ad80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 28.602147] ================================================================== [ 28.609479] Disabling lock debugging due to kernel taint [ 28.615547] Kernel panic - not syncing: panic_on_warn set ... [ 28.615547] [ 28.622907] CPU: 0 PID: 4189 Comm: syz-executor0 Tainted: G B 4.9.113-g8956c50 #19 [ 28.631714] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.641045] ffff8801d4fd7c00 ffffffff81eb32a9 ffffffff843c806f 00000000ffffffff [ 28.649039] 0000000000000000 0000000000000000 ffffffff83013be0 ffff8801d4fd7cc0 [ 28.657046] ffffffff81421a55 0000000041b58ab3 ffffffff843bb788 ffffffff81421896 [ 28.665059] Call Trace: [ 28.667626] [] dump_stack+0xc1/0x128 [ 28.672966] [] ? sock_release+0x1c0/0x1c0 [ 28.678740] [] panic+0x1bf/0x3bc [ 28.683730] [] ? add_taint.cold.6+0x16/0x16 [ 28.689684] [] ? ___preempt_schedule+0x16/0x18 [ 28.695894] [] kasan_end_report+0x47/0x4f [ 28.701664] [] kasan_report.cold.6+0x76/0x2fe [ 28.707788] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 28.714526] [] __asan_report_load4_noabort+0x14/0x20 [ 28.721256] [] l2tp_session_queue_purge+0xf4/0x100 [ 28.727814] [] ? sock_release+0x1c0/0x1c0 [ 28.733587] [] pppol2tp_release+0x1fb/0x2e0 [ 28.739531] [] sock_release+0x96/0x1c0 [ 28.745043] [] sock_close+0x16/0x20 [ 28.750298] [] __fput+0x263/0x700 [ 28.755375] [] ____fput+0x15/0x20 [ 28.760452] [] task_work_run+0x10c/0x180 [ 28.766141] [] exit_to_usermode_loop+0xfc/0x120 [ 28.772441] [] do_fast_syscall_32+0x5c3/0x870 [ 28.778562] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 28.785203] [] entry_SYSENTER_compat+0x90/0xa2 [ 28.791820] Dumping ftrace buffer: [ 28.795343] (ftrace buffer empty) [ 28.799040] Kernel Offset: disabled [ 28.802642] Rebooting in 86400 seconds..