[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.430446] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.079615] random: sshd: uninitialized urandom read (32 bytes read) [ 15.446762] random: sshd: uninitialized urandom read (32 bytes read) [ 15.947176] random: sshd: uninitialized urandom read (32 bytes read) [ 16.446880] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.35' (ECDSA) to the list of known hosts. [ 22.068694] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/06 20:02:17 parsed 1 programs [ 23.622508] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/06 20:02:19 executed programs: 0 [ 24.688258] IPVS: Creating netns size=2536 id=1 [ 24.810123] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 24.821536] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 24.864140] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 24.875616] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 24.918136] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 24.929607] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 24.941175] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 24.961798] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 25.446223] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 25.470874] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 25.477375] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 25.484621] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 27.062306] ================================================================== [ 27.069807] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 27.077071] Read of size 4 at addr ffff8801da255180 by task syz-executor0/4267 [ 27.084404] [ 27.086011] CPU: 0 PID: 4267 Comm: syz-executor0 Not tainted 4.9.118-g47b77b8 #24 [ 27.093603] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.102942] ffff8801c71afca0 ffffffff81eb4b89 ffffea0007689500 ffff8801da255180 [ 27.110948] 0000000000000000 ffff8801da255180 ffffffff83015be0 ffff8801c71afcd8 [ 27.119267] ffffffff81567f29 ffff8801da255180 0000000000000004 0000000000000000 [ 27.127266] Call Trace: [ 27.129839] [] dump_stack+0xc1/0x128 [ 27.135185] [] ? sock_release+0x1c0/0x1c0 [ 27.141050] [] print_address_description+0x6c/0x234 [ 27.147710] [] ? sock_release+0x1c0/0x1c0 [ 27.153486] [] kasan_report.cold.6+0x242/0x2fe [ 27.159703] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 27.166433] [] __asan_report_load4_noabort+0x14/0x20 [ 27.173164] [] l2tp_session_queue_purge+0xf4/0x100 [ 27.179819] [] ? sock_release+0x1c0/0x1c0 [ 27.185617] [] pppol2tp_release+0x1fb/0x2e0 [ 27.191576] [] sock_release+0x96/0x1c0 [ 27.197094] [] sock_close+0x16/0x20 [ 27.202365] [] __fput+0x263/0x700 [ 27.207449] [] ____fput+0x15/0x20 [ 27.212536] [] task_work_run+0x10c/0x180 [ 27.218230] [] exit_to_usermode_loop+0xfc/0x120 [ 27.224532] [] do_fast_syscall_32+0x5c3/0x870 [ 27.230657] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.237313] [] entry_SYSENTER_compat+0x90/0xa2 [ 27.243519] [ 27.245122] Allocated by task 4268: [ 27.248736] save_stack_trace+0x16/0x20 [ 27.252864] save_stack+0x43/0xd0 [ 27.256293] kasan_kmalloc+0xc7/0xe0 [ 27.260103] __kmalloc+0x11d/0x300 [ 27.263637] l2tp_session_create+0x38/0x16f0 [ 27.268023] pppol2tp_connect+0x10d7/0x18f0 [ 27.272322] SYSC_connect+0x1b8/0x300 [ 27.276098] SyS_connect+0x24/0x30 [ 27.279619] do_fast_syscall_32+0x2f7/0x870 [ 27.283918] entry_SYSENTER_compat+0x90/0xa2 [ 27.288296] [ 27.289899] Freed by task 4258: [ 27.293165] save_stack_trace+0x16/0x20 [ 27.297121] save_stack+0x43/0xd0 [ 27.300548] kasan_slab_free+0x72/0xc0 [ 27.304414] kfree+0xfb/0x310 [ 27.307502] l2tp_session_free+0x166/0x200 [ 27.311720] l2tp_tunnel_closeall+0x284/0x350 [ 27.316189] l2tp_udp_encap_destroy+0x87/0xe0 [ 27.320663] udpv6_destroy_sock+0xb1/0xd0 [ 27.324799] sk_common_release+0x6d/0x300 [ 27.328922] udp_lib_close+0x15/0x20 [ 27.332632] inet_release+0xff/0x1d0 [ 27.336332] inet6_release+0x50/0x70 [ 27.340035] sock_release+0x96/0x1c0 [ 27.343730] sock_close+0x16/0x20 [ 27.347167] __fput+0x263/0x700 [ 27.350421] ____fput+0x15/0x20 [ 27.353679] task_work_run+0x10c/0x180 [ 27.357541] do_exit+0x9e1/0x27b0 [ 27.360969] do_group_exit+0x111/0x340 [ 27.364953] get_signal+0x4cf/0x1450 [ 27.368645] do_signal+0x87/0x19f0 [ 27.372169] exit_to_usermode_loop+0xe1/0x120 [ 27.376651] prepare_exit_to_usermode+0xbb/0xe0 [ 27.381304] retint_user+0x8/0x3c [ 27.384727] [ 27.386327] The buggy address belongs to the object at ffff8801da255180 [ 27.386327] which belongs to the cache kmalloc-512 of size 512 [ 27.398958] The buggy address is located 0 bytes inside of [ 27.398958] 512-byte region [ffff8801da255180, ffff8801da255380) [ 27.410627] The buggy address belongs to the page: [ 27.415629] page:ffffea0007689500 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 27.425805] flags: 0x8000000000004080(slab|head) [ 27.430529] page dumped because: kasan: bad access detected [ 27.436346] [ 27.437948] Memory state around the buggy address: [ 27.442851] ffff8801da255080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.450250] ffff8801da255100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 27.457669] >ffff8801da255180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.465491] ^ [ 27.468837] ffff8801da255200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.476172] ffff8801da255280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 27.483503] ================================================================== [ 27.490836] Disabling lock debugging due to kernel taint [ 27.496789] Kernel panic - not syncing: panic_on_warn set ... [ 27.496789] [ 27.504143] CPU: 0 PID: 4267 Comm: syz-executor0 Tainted: G B 4.9.118-g47b77b8 #24 [ 27.512949] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.522277] ffff8801c71afc00 ffffffff81eb4b89 ffffffff843c8907 00000000ffffffff [ 27.530379] 0000000000000000 0000000000000000 ffffffff83015be0 ffff8801c71afcc0 [ 27.538356] ffffffff81421c25 0000000041b58ab3 ffffffff843bbfe8 ffffffff81421a66 [ 27.546444] Call Trace: [ 27.549093] [] dump_stack+0xc1/0x128 [ 27.554437] [] ? sock_release+0x1c0/0x1c0 [ 27.560207] [] panic+0x1bf/0x3bc [ 27.565197] [] ? add_taint.cold.6+0x16/0x16 [ 27.571141] [] ? ___preempt_schedule+0x16/0x18 [ 27.577343] [] kasan_end_report+0x47/0x4f [ 27.583113] [] kasan_report.cold.6+0x76/0x2fe [ 27.589229] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 27.596186] [] __asan_report_load4_noabort+0x14/0x20 [ 27.603024] [] l2tp_session_queue_purge+0xf4/0x100 [ 27.609580] [] ? sock_release+0x1c0/0x1c0 [ 27.615353] [] pppol2tp_release+0x1fb/0x2e0 [ 27.621297] [] sock_release+0x96/0x1c0 [ 27.626964] [] sock_close+0x16/0x20 [ 27.632218] [] __fput+0x263/0x700 [ 27.637294] [] ____fput+0x15/0x20 [ 27.642373] [] task_work_run+0x10c/0x180 [ 27.648054] [] exit_to_usermode_loop+0xfc/0x120 [ 27.654344] [] do_fast_syscall_32+0x5c3/0x870 [ 27.660595] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.667236] [] entry_SYSENTER_compat+0x90/0xa2 [ 27.673777] Dumping ftrace buffer: [ 27.677385] (ftrace buffer empty) [ 27.681068] Kernel Offset: disabled [ 27.684666] Rebooting in 86400 seconds..