[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.371361] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.377141] random: sshd: uninitialized urandom read (32 bytes read) [ 18.750448] random: sshd: uninitialized urandom read (32 bytes read) [ 19.262921] random: sshd: uninitialized urandom read (32 bytes read) [ 19.408101] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.60' (ECDSA) to the list of known hosts. [ 24.878680] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/09 00:46:50 parsed 1 programs [ 26.021468] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/09 00:46:52 executed programs: 0 [ 27.604656] IPVS: Creating netns size=2536 id=1 [ 27.724563] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 27.735903] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 27.777457] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 27.788500] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 27.832580] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 27.843894] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 27.855529] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 27.875993] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 28.353547] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 28.378460] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 28.384576] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 28.391265] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 28.562926] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 28.574964] l2tp_core: tunl 3: sockfd_lookup(fd=16) returned -9 [ 28.595299] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 28.607311] l2tp_core: tunl 3: sockfd_lookup(fd=16) returned -9 [ 28.624860] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 28.637753] l2tp_core: tunl 3: sockfd_lookup(fd=16) returned -9 [ 28.655286] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 28.666721] l2tp_core: tunl 3: sockfd_lookup(fd=16) returned -9 [ 28.688291] l2tp_core: tunl 3: sockfd_lookup(fd=9) returned -9 [ 28.761921] ================================================================== [ 28.769379] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 28.776637] Read of size 4 at addr ffff8801d8364780 by task syz-executor0/4211 [ 28.783970] [ 28.785578] CPU: 0 PID: 4211 Comm: syz-executor0 Not tainted 4.9.118-g856452b #21 [ 28.793169] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.802500] ffff8801d5367cb0 ffffffff81eb4b89 ffffea000760d900 ffff8801d8364780 [ 28.810484] 0000000000000000 ffff8801d8364780 ffffffff83015be0 ffff8801d5367ce8 [ 28.818489] ffffffff81567f29 ffff8801d8364780 0000000000000004 0000000000000000 [ 28.826466] Call Trace: [ 28.829192] [] dump_stack+0xc1/0x128 [ 28.834543] [] ? sock_release+0x1c0/0x1c0 [ 28.840331] [] print_address_description+0x6c/0x234 [ 28.846970] [] ? sock_release+0x1c0/0x1c0 [ 28.852739] [] kasan_report.cold.6+0x242/0x2fe [ 28.858947] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 28.865675] [] __asan_report_load4_noabort+0x14/0x20 [ 28.872410] [] l2tp_session_queue_purge+0xf4/0x100 [ 28.878968] [] ? sock_release+0x1c0/0x1c0 [ 28.884874] [] pppol2tp_release+0x1fb/0x2e0 [ 28.890831] [] sock_release+0x96/0x1c0 [ 28.896345] [] sock_close+0x16/0x20 [ 28.901605] [] __fput+0x263/0x700 [ 28.906680] [] ____fput+0x15/0x20 [ 28.911757] [] task_work_run+0x10c/0x180 [ 28.917496] [] exit_to_usermode_loop+0xfc/0x120 [ 28.923797] [] do_syscall_64+0x364/0x490 [ 28.929483] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.936506] [ 28.938121] Allocated by task 4215: [ 28.941729] save_stack_trace+0x16/0x20 [ 28.945679] save_stack+0x43/0xd0 [ 28.949104] kasan_kmalloc+0xc7/0xe0 [ 28.952836] __kmalloc+0x11d/0x300 [ 28.956360] l2tp_session_create+0x38/0x16f0 [ 28.960746] pppol2tp_connect+0x10d7/0x18f0 [ 28.965044] SYSC_connect+0x1b8/0x300 [ 28.968818] SyS_connect+0x24/0x30 [ 28.972334] do_syscall_64+0x1a6/0x490 [ 28.976195] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.981267] [ 28.982872] Freed by task 4215: [ 28.986137] save_stack_trace+0x16/0x20 [ 28.990094] save_stack+0x43/0xd0 [ 28.993519] kasan_slab_free+0x72/0xc0 [ 28.997382] kfree+0xfb/0x310 [ 29.000465] l2tp_session_free+0x166/0x200 [ 29.004685] l2tp_tunnel_closeall+0x284/0x350 [ 29.009229] l2tp_udp_encap_destroy+0x87/0xe0 [ 29.013715] udp_destroy_sock+0x118/0x1a0 [ 29.017838] sk_common_release+0x6d/0x300 [ 29.021962] udp_lib_close+0x15/0x20 [ 29.025652] inet_release+0xff/0x1d0 [ 29.029339] sock_release+0x96/0x1c0 [ 29.033028] sock_close+0x16/0x20 [ 29.036457] __fput+0x263/0x700 [ 29.039708] ____fput+0x15/0x20 [ 29.042964] task_work_run+0x10c/0x180 [ 29.046833] exit_to_usermode_loop+0xfc/0x120 [ 29.051314] do_syscall_64+0x364/0x490 [ 29.055173] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.060243] [ 29.061844] The buggy address belongs to the object at ffff8801d8364780 [ 29.061844] which belongs to the cache kmalloc-512 of size 512 [ 29.074472] The buggy address is located 0 bytes inside of [ 29.074472] 512-byte region [ffff8801d8364780, ffff8801d8364980) [ 29.086143] The buggy address belongs to the page: [ 29.091046] page:ffffea000760d900 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 29.101319] flags: 0x8000000000004080(slab|head) [ 29.106043] page dumped because: kasan: bad access detected [ 29.111723] [ 29.113324] Memory state around the buggy address: [ 29.118226] ffff8801d8364680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.125557] ffff8801d8364700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 29.132888] >ffff8801d8364780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.140219] ^ [ 29.143562] ffff8801d8364800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.150895] ffff8801d8364880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 29.158226] ================================================================== [ 29.165557] Disabling lock debugging due to kernel taint [ 29.171492] Kernel panic - not syncing: panic_on_warn set ... [ 29.171492] [ 29.178913] CPU: 0 PID: 4211 Comm: syz-executor0 Tainted: G B 4.9.118-g856452b #21 [ 29.187725] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.197052] ffff8801d5367c10 ffffffff81eb4b89 ffffffff843c8907 00000000ffffffff [ 29.205034] 0000000000000000 0000000000000000 ffffffff83015be0 ffff8801d5367cd0 [ 29.213051] ffffffff81421c25 0000000041b58ab3 ffffffff843bbfe8 ffffffff81421a66 [ 29.221035] Call Trace: [ 29.223608] [] dump_stack+0xc1/0x128 [ 29.228952] [] ? sock_release+0x1c0/0x1c0 [ 29.234726] [] panic+0x1bf/0x3bc [ 29.239718] [] ? add_taint.cold.6+0x16/0x16 [ 29.245678] [] ? ___preempt_schedule+0x16/0x18 [ 29.251886] [] kasan_end_report+0x47/0x4f [ 29.257659] [] kasan_report.cold.6+0x76/0x2fe [ 29.263778] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 29.270504] [] __asan_report_load4_noabort+0x14/0x20 [ 29.277229] [] l2tp_session_queue_purge+0xf4/0x100 [ 29.283830] [] ? sock_release+0x1c0/0x1c0 [ 29.289610] [] pppol2tp_release+0x1fb/0x2e0 [ 29.295557] [] sock_release+0x96/0x1c0 [ 29.301069] [] sock_close+0x16/0x20 [ 29.306322] [] __fput+0x263/0x700 [ 29.311401] [] ____fput+0x15/0x20 [ 29.316485] [] task_work_run+0x10c/0x180 [ 29.322173] [] exit_to_usermode_loop+0xfc/0x120 [ 29.328473] [] do_syscall_64+0x364/0x490 [ 29.334163] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.341333] Dumping ftrace buffer: [ 29.344853] (ftrace buffer empty) [ 29.348538] Kernel Offset: disabled [ 29.352136] Rebooting in 86400 seconds..