[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.859336] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.106871] random: sshd: uninitialized urandom read (32 bytes read) [ 20.666108] random: sshd: uninitialized urandom read (32 bytes read) [ 21.657645] random: sshd: uninitialized urandom read (32 bytes read) [ 32.638488] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.2' (ECDSA) to the list of known hosts. [ 38.013943] random: sshd: uninitialized urandom read (32 bytes read) 2018/06/10 22:10:27 parsed 1 programs [ 39.215373] random: cc1: uninitialized urandom read (8 bytes read) 2018/06/10 22:10:29 executed programs: 0 [ 40.352105] IPVS: Creating netns size=2536 id=1 [ 40.440582] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 40.451794] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 40.495221] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 40.507705] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 40.554426] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 40.566700] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 40.579463] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 40.600074] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 41.093629] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 41.117786] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 41.123937] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 41.131519] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 42.936455] ================================================================== [ 42.943847] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 42.951091] Read of size 4 at addr ffff8801d4908000 by task syz-executor0/4177 [ 42.958417] [ 42.960024] CPU: 1 PID: 4177 Comm: syz-executor0 Not tainted 4.9.107-gdb2c520 #49 [ 42.967613] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 42.976939] ffff8801d4d67ca0 ffffffff81eb3da9 ffffea0007524200 ffff8801d4908000 [ 42.984917] 0000000000000000 ffff8801d4908000 ffffffff83013be0 ffff8801d4d67cd8 [ 42.992927] ffffffff815679f9 ffff8801d4908000 0000000000000004 0000000000000000 [ 43.000905] Call Trace: [ 43.003475] [] dump_stack+0xc1/0x128 [ 43.008812] [] ? sock_release+0x1c0/0x1c0 [ 43.014580] [] print_address_description+0x6c/0x234 [ 43.021222] [] ? sock_release+0x1c0/0x1c0 [ 43.026992] [] kasan_report.cold.6+0x242/0x2fe [ 43.033203] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 43.039936] [] __asan_report_load4_noabort+0x14/0x20 [ 43.046660] [] l2tp_session_queue_purge+0xf4/0x100 [ 43.053211] [] ? sock_release+0x1c0/0x1c0 [ 43.058979] [] pppol2tp_release+0x1fb/0x2e0 [ 43.064927] [] sock_release+0x96/0x1c0 [ 43.070436] [] sock_close+0x16/0x20 [ 43.075687] [] __fput+0x263/0x700 [ 43.080768] [] ____fput+0x15/0x20 [ 43.085854] [] task_work_run+0x10c/0x180 [ 43.091540] [] exit_to_usermode_loop+0xfc/0x120 [ 43.097840] [] do_fast_syscall_32+0x5c3/0x870 [ 43.103957] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 43.110596] [] entry_SYSENTER_compat+0x90/0xa2 [ 43.116805] [ 43.118405] Allocated by task 4177: [ 43.122013] save_stack_trace+0x16/0x20 [ 43.125960] save_stack+0x43/0xd0 [ 43.129392] kasan_kmalloc+0xc7/0xe0 [ 43.133089] __kmalloc+0x11d/0x300 [ 43.136600] l2tp_session_create+0x38/0x16f0 [ 43.140984] pppol2tp_connect+0x10d7/0x18f0 [ 43.145282] SYSC_connect+0x1b8/0x300 [ 43.149241] SyS_connect+0x24/0x30 [ 43.152754] do_fast_syscall_32+0x2f7/0x870 [ 43.157048] entry_SYSENTER_compat+0x90/0xa2 [ 43.161430] [ 43.163039] Freed by task 4178: [ 43.166300] save_stack_trace+0x16/0x20 [ 43.170266] save_stack+0x43/0xd0 [ 43.173723] kasan_slab_free+0x72/0xc0 [ 43.177684] kfree+0xfb/0x310 [ 43.180772] l2tp_session_free+0x166/0x200 [ 43.184980] l2tp_tunnel_closeall+0x284/0x350 [ 43.189456] l2tp_udp_encap_destroy+0x87/0xe0 [ 43.193943] udpv6_destroy_sock+0xb1/0xd0 [ 43.198078] sk_common_release+0x6d/0x300 [ 43.202197] udp_lib_close+0x15/0x20 [ 43.205885] inet_release+0xff/0x1d0 [ 43.209571] inet6_release+0x50/0x70 [ 43.213271] sock_release+0x96/0x1c0 [ 43.216964] sock_close+0x16/0x20 [ 43.220401] __fput+0x263/0x700 [ 43.223650] ____fput+0x15/0x20 [ 43.226901] task_work_run+0x10c/0x180 [ 43.230765] exit_to_usermode_loop+0xfc/0x120 [ 43.235229] do_fast_syscall_32+0x5c3/0x870 [ 43.239537] entry_SYSENTER_compat+0x90/0xa2 [ 43.243925] [ 43.245548] The buggy address belongs to the object at ffff8801d4908000 [ 43.245548] which belongs to the cache kmalloc-512 of size 512 [ 43.258179] The buggy address is located 0 bytes inside of [ 43.258179] 512-byte region [ffff8801d4908000, ffff8801d4908200) [ 43.269873] The buggy address belongs to the page: [ 43.274790] page:ffffea0007524200 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 43.284967] flags: 0x8000000000004080(slab|head) [ 43.289694] page dumped because: kasan: bad access detected [ 43.295373] [ 43.296992] Memory state around the buggy address: [ 43.301897] ffff8801d4907f00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 43.309245] ffff8801d4907f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 43.316585] >ffff8801d4908000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.323926] ^ [ 43.327268] ffff8801d4908080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.334602] ffff8801d4908100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 43.341940] ================================================================== [ 43.349275] Disabling lock debugging due to kernel taint [ 43.355071] Kernel panic - not syncing: panic_on_warn set ... [ 43.355071] [ 43.362417] CPU: 1 PID: 4177 Comm: syz-executor0 Tainted: G B 4.9.107-gdb2c520 #49 [ 43.371231] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 43.380569] ffff8801d4d67c00 ffffffff81eb3da9 ffffffff843c6427 00000000ffffffff [ 43.388584] 0000000000000000 0000000000000001 ffffffff83013be0 ffff8801d4d67cc0 [ 43.396566] ffffffff81421925 0000000041b58ab3 ffffffff843b9b48 ffffffff81421766 [ 43.404546] Call Trace: [ 43.407110] [] dump_stack+0xc1/0x128 [ 43.412460] [] ? sock_release+0x1c0/0x1c0 [ 43.418234] [] panic+0x1bf/0x3bc [ 43.423230] [] ? add_taint.cold.6+0x16/0x16 [ 43.429175] [] ? ___preempt_schedule+0x16/0x18 [ 43.435392] [] kasan_end_report+0x47/0x4f [ 43.441161] [] kasan_report.cold.6+0x76/0x2fe [ 43.447287] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 43.454109] [] __asan_report_load4_noabort+0x14/0x20 [ 43.460842] [] l2tp_session_queue_purge+0xf4/0x100 [ 43.467393] [] ? sock_release+0x1c0/0x1c0 [ 43.473165] [] pppol2tp_release+0x1fb/0x2e0 [ 43.479116] [] sock_release+0x96/0x1c0 [ 43.484624] [] sock_close+0x16/0x20 [ 43.489877] [] __fput+0x263/0x700 [ 43.494968] [] ____fput+0x15/0x20 [ 43.500052] [] task_work_run+0x10c/0x180 [ 43.505752] [] exit_to_usermode_loop+0xfc/0x120 [ 43.512044] [] do_fast_syscall_32+0x5c3/0x870 [ 43.518163] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 43.524804] [] entry_SYSENTER_compat+0x90/0xa2 [ 43.531579] Dumping ftrace buffer: [ 43.535093] (ftrace buffer empty) [ 43.538776] Kernel Offset: disabled [ 43.542375] Rebooting in 86400 seconds..