[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.980145] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.901362] random: sshd: uninitialized urandom read (32 bytes read) [ 20.431383] random: sshd: uninitialized urandom read (32 bytes read) [ 20.955075] random: sshd: uninitialized urandom read (32 bytes read) [ 31.830724] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.47' (ECDSA) to the list of known hosts. [ 37.348380] random: sshd: uninitialized urandom read (32 bytes read) 2018/08/22 14:48:15 parsed 1 programs [ 39.013403] random: cc1: uninitialized urandom read (8 bytes read) 2018/08/22 14:48:18 executed programs: 0 [ 40.471166] IPVS: Creating netns size=2536 id=1 [ 40.597460] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 40.609320] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 40.654438] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 40.665996] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 40.711370] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 40.724644] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 40.737078] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 40.750613] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 41.276561] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 41.301445] IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready [ 41.307793] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready [ 41.315337] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 41.524768] hrtimer: interrupt took 17888 ns [ 42.195477] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 43.324899] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 44.154093] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 44.423856] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 44.950198] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 45.345427] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 2018/08/22 14:48:23 executed programs: 428 [ 45.798071] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.020308] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.078344] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.438286] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.615787] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.855225] l2tp_core: tunl 4: sockfd_lookup(fd=6) returned -9 [ 46.913872] ================================================================== [ 46.921254] BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xed/0x110 [ 46.928598] Read of size 4 at addr ffff8801cde81b80 by task syz-executor0/6284 [ 46.935946] [ 46.937566] CPU: 1 PID: 6284 Comm: syz-executor0 Not tainted 4.9.123-g8dd3fc2 #31 [ 46.945160] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.954495] ffff8801ceac7c20 ffffffff81eb9689 ffffea000737a000 ffff8801cde81b80 [ 46.962529] 0000000000000000 ffff8801cde81b80 ffffffff8301abe0 ffff8801ceac7c58 [ 46.970581] ffffffff8156c3fe ffff8801cde81b80 0000000000000004 0000000000000000 [ 46.978660] Call Trace: [ 46.981234] [] dump_stack+0xc1/0x128 [ 46.986581] [] ? sock_release+0x1c0/0x1c0 [ 46.992358] [] print_address_description+0x6c/0x234 [ 46.999000] [] ? sock_release+0x1c0/0x1c0 [ 47.004779] [] kasan_report.cold.6+0x242/0x2fe [ 47.011008] [] ? pppol2tp_session_destruct+0xed/0x110 [ 47.017838] [] __asan_report_load4_noabort+0x14/0x20 [ 47.024565] [] pppol2tp_session_destruct+0xed/0x110 [ 47.031236] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 47.037546] [] __sk_destruct+0x55/0x590 [ 47.043161] [] ? sock_release+0x1c0/0x1c0 [ 47.048954] [] sk_destruct+0x63/0x80 [ 47.054306] [] __sk_free+0x4f/0x220 [ 47.059561] [] sk_free+0x2b/0x40 [ 47.064557] [] pppol2tp_release+0x239/0x2e0 [ 47.070506] [] sock_release+0x96/0x1c0 [ 47.076020] [] sock_close+0x16/0x20 [ 47.081274] [] __fput+0x263/0x700 [ 47.086355] [] ____fput+0x15/0x20 [ 47.091447] [] task_work_run+0x10c/0x180 [ 47.097139] [] exit_to_usermode_loop+0xfc/0x120 [ 47.103441] [] do_fast_syscall_32+0x5c3/0x870 [ 47.109564] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 47.116205] [] entry_SYSENTER_compat+0x90/0xa2 [ 47.122408] [ 47.124016] Allocated by task 6285: [ 47.127619] save_stack_trace+0x16/0x20 [ 47.131568] save_stack+0x43/0xd0 [ 47.134995] kasan_kmalloc+0xc7/0xe0 [ 47.138870] __kmalloc+0x11d/0x300 [ 47.142398] l2tp_session_create+0x38/0x16f0 [ 47.146785] pppol2tp_connect+0x10d7/0x18f0 [ 47.151086] SYSC_connect+0x1b8/0x300 [ 47.154862] SyS_connect+0x24/0x30 [ 47.158377] do_fast_syscall_32+0x2f7/0x870 [ 47.162681] entry_SYSENTER_compat+0x90/0xa2 [ 47.167059] [ 47.168671] Freed by task 6285: [ 47.171927] save_stack_trace+0x16/0x20 [ 47.175882] save_stack+0x43/0xd0 [ 47.179309] kasan_slab_free+0x72/0xc0 [ 47.183179] kfree+0xfb/0x310 [ 47.186278] l2tp_session_free+0x166/0x200 [ 47.190512] l2tp_tunnel_closeall+0x284/0x350 [ 47.190518] l2tp_udp_encap_destroy+0x87/0xe0 [ 47.190524] udpv6_destroy_sock+0xb1/0xd0 [ 47.190531] sk_common_release+0x6d/0x300 [ 47.190536] udp_lib_close+0x15/0x20 [ 47.190547] inet_release+0xff/0x1d0 [ 47.190554] inet6_release+0x50/0x70 [ 47.190560] sock_release+0x96/0x1c0 [ 47.190565] sock_close+0x16/0x20 [ 47.190571] __fput+0x263/0x700 [ 47.190576] ____fput+0x15/0x20 [ 47.190584] task_work_run+0x10c/0x180 [ 47.190590] exit_to_usermode_loop+0xfc/0x120 [ 47.190596] do_fast_syscall_32+0x5c3/0x870 [ 47.190603] entry_SYSENTER_compat+0x90/0xa2 [ 47.190605] [ 47.190610] The buggy address belongs to the object at ffff8801cde81b80 [ 47.190610] which belongs to the cache kmalloc-512 of size 512 [ 47.190616] The buggy address is located 0 bytes inside of [ 47.190616] 512-byte region [ffff8801cde81b80, ffff8801cde81d80) [ 47.190618] The buggy address belongs to the page: [ 47.190629] page:ffffea000737a000 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 47.190633] flags: 0x8000000000004080(slab|head) [ 47.190636] page dumped because: kasan: bad access detected [ 47.190637] [ 47.190639] Memory state around the buggy address: [ 47.190646] ffff8801cde81a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.190651] ffff8801cde81b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 47.190656] >ffff8801cde81b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.190658] ^ [ 47.190676] ffff8801cde81c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.190681] ffff8801cde81c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.190684] ================================================================== [ 47.190685] Disabling lock debugging due to kernel taint [ 47.196853] Kernel panic - not syncing: panic_on_warn set ... [ 47.196853] [ 47.196864] CPU: 1 PID: 6284 Comm: syz-executor0 Tainted: G B 4.9.123-g8dd3fc2 #31 [ 47.196868] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 47.196879] ffff8801ceac7b80 ffffffff81eb9689 ffffffff843c821b 00000000ffffffff [ 47.196888] 0000000000000000 0000000000000001 ffffffff8301abe0 ffff8801ceac7c40 [ 47.196898] ffffffff81423f75 0000000041b58ab3 ffffffff843bb878 ffffffff81423db6 [ 47.196899] Call Trace: [ 47.196910] [] dump_stack+0xc1/0x128 [ 47.196918] [] ? sock_release+0x1c0/0x1c0 [ 47.196927] [] panic+0x1bf/0x3bc [ 47.196934] [] ? add_taint.cold.6+0x16/0x16 [ 47.196942] [] ? ___preempt_schedule+0x16/0x18 [ 47.196949] [] kasan_end_report+0x47/0x4f [ 47.196956] [] kasan_report.cold.6+0x76/0x2fe [ 47.196964] [] ? pppol2tp_session_destruct+0xed/0x110 [ 47.196972] [] __asan_report_load4_noabort+0x14/0x20 [ 47.196979] [] pppol2tp_session_destruct+0xed/0x110 [ 47.196985] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 47.196992] [] __sk_destruct+0x55/0x590 [ 47.196999] [] ? sock_release+0x1c0/0x1c0 [ 47.197006] [] sk_destruct+0x63/0x80 [ 47.197012] [] __sk_free+0x4f/0x220 [ 47.197019] [] sk_free+0x2b/0x40 [ 47.197026] [] pppol2tp_release+0x239/0x2e0 [ 47.197033] [] sock_release+0x96/0x1c0 [ 47.197040] [] sock_close+0x16/0x20 [ 47.197048] [] __fput+0x263/0x700 [ 47.197055] [] ____fput+0x15/0x20 [ 47.197063] [] task_work_run+0x10c/0x180 [ 47.197070] [] exit_to_usermode_loop+0xfc/0x120 [ 47.197077] [] do_fast_syscall_32+0x5c3/0x870 [ 47.197084] [] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 47.197092] [] entry_SYSENTER_compat+0x90/0xa2 [ 47.201613] Dumping ftrace buffer: [ 47.201617] (ftrace buffer empty) [ 47.201620] Kernel Offset: disabled [ 47.574590] Rebooting in 86400 seconds..