[ 16.025991] random: sshd: uninitialized urandom read (32 bytes read, 32 bits of entropy available) [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.206391] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [ 20.405839] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [ 21.285100] random: sshd: uninitialized urandom read (32 bytes read, 104 bits of entropy available) [ 21.452249] random: sshd: uninitialized urandom read (32 bytes read, 108 bits of entropy available) Warning: Permanently added '10.128.15.207' (ECDSA) to the list of known hosts. [ 26.834943] random: sshd: uninitialized urandom read (32 bytes read, 114 bits of entropy available) net.ipv6.conf.syz0.accept_dad = 0 net.ipv6.conf.syz0.router_solicitations = 0 RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported RTNETLINK answers: Operation not supported Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "bridge0" Cannot find device "vcan0" Cannot find device "vcan0" Cannot find device "vcan0" Cannot find device "vcan0" RTNETLINK answers: Operation not supported Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gre0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "gretap0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6_vti0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6tnl0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gre0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "ip6gretap0" Cannot find device "erspan0" Cannot find device "erspan0" Cannot find device "erspan0" Cannot find device "erspan0" executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 28.217797] ================================================================== [ 28.225173] BUG: KASAN: use-after-free in pppol2tp_session_destruct+0xee/0x110 [ 28.232501] Read of size 4 at addr ffff8800b2a74280 by task syzkaller617982/3530 [ 28.240004] [ 28.241608] CPU: 1 PID: 3530 Comm: syzkaller617982 Not tainted 4.4.113-gef588ef #26 [ 28.249369] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.258688] 0000000000000000 186d8abf915aa594 ffff8801cec37c20 ffffffff81d0278d [ 28.266652] ffffea0002ca9d00 ffff8800b2a74280 0000000000000000 ffff8800b2a74280 [ 28.274607] ffffffff82de6370 ffff8801cec37c58 ffffffff814fd053 ffff8800b2a74280 [ 28.282562] Call Trace: [ 28.285118] [] dump_stack+0xc1/0x124 [ 28.290452] [] ? sock_release+0x1e0/0x1e0 [ 28.296216] [] print_address_description+0x73/0x260 [ 28.302846] [] ? sock_release+0x1e0/0x1e0 [ 28.308607] [] kasan_report+0x285/0x370 [ 28.314200] [] ? pppol2tp_session_destruct+0xee/0x110 [ 28.321007] [] __asan_report_load4_noabort+0x14/0x20 [ 28.327725] [] pppol2tp_session_destruct+0xee/0x110 [ 28.334360] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.340644] [] sk_destruct+0x4a/0x4c0 [ 28.346081] [] __sk_free+0x57/0x230 [ 28.351344] [] sk_free+0x30/0x40 [ 28.356325] [] pppol2tp_release+0x27a/0x310 [ 28.362262] [] sock_release+0x8d/0x1e0 [ 28.367773] [] sock_close+0x16/0x20 [ 28.373018] [] __fput+0x233/0x6d0 [ 28.378088] [] ____fput+0x15/0x20 [ 28.383161] [] task_work_run+0x104/0x180 [ 28.388839] [] exit_to_usermode_loop+0x13d/0x160 [ 28.395210] [] do_fast_syscall_32+0x607/0x890 [ 28.401320] [] sysenter_flags_fixed+0xd/0x17 [ 28.407341] [ 28.408936] Allocated by task 3529: [ 28.412525] [] save_stack_trace+0x26/0x50 [ 28.418416] [] save_stack+0x43/0xd0 [ 28.423774] [] kasan_kmalloc+0xad/0xe0 [ 28.429393] [] __kmalloc+0x124/0x320 [ 28.434835] [] l2tp_session_create+0x39/0x10f0 [ 28.441149] [] pppol2tp_connect+0x10fc/0x1930 [ 28.447371] [] SYSC_connect+0x1b6/0x310 [ 28.453094] [] SyS_connect+0x24/0x30 [ 28.458545] [] do_fast_syscall_32+0x314/0x890 [ 28.464773] [] sysenter_flags_fixed+0xd/0x17 [ 28.470911] [ 28.472510] Freed by task 3529: [ 28.475752] [] save_stack_trace+0x26/0x50 [ 28.481632] [] save_stack+0x43/0xd0 [ 28.486993] [] kasan_slab_free+0x72/0xc0 [ 28.492784] [] kfree+0xfc/0x300 [ 28.497796] [] l2tp_session_free+0x170/0x200 [ 28.503933] [] l2tp_tunnel_closeall+0x2d1/0x3b0 [ 28.510333] [] l2tp_udp_encap_destroy+0x8b/0xf0 [ 28.516730] [] udpv6_destroy_sock+0xb1/0xd0 [ 28.522797] [] sk_common_release+0x6b/0x300 [ 28.528850] [] udp_lib_close+0x15/0x20 [ 28.534463] [] inet_release+0xfa/0x1d0 [ 28.540079] [] inet6_release+0x50/0x70 [ 28.545698] [] sock_release+0x8d/0x1e0 [ 28.551316] [] sock_close+0x16/0x20 [ 28.556675] [] __fput+0x233/0x6d0 [ 28.561858] [] ____fput+0x15/0x20 [ 28.567043] [] task_work_run+0x104/0x180 [ 28.572840] [] exit_to_usermode_loop+0x13d/0x160 [ 28.579327] [] do_fast_syscall_32+0x607/0x890 [ 28.585550] [] sysenter_flags_fixed+0xd/0x17 [ 28.591688] [ 28.593284] The buggy address belongs to the object at ffff8800b2a74280 [ 28.593284] which belongs to the cache kmalloc-512 of size 512 [ 28.605905] The buggy address is located 0 bytes inside of [ 28.605905] 512-byte region [ffff8800b2a74280, ffff8800b2a74480) [ 28.617575] The buggy address belongs to the page: [ 30.068283] PANIC: double fault, error_code: 0x0 [ 30.073059] CPU: 1 PID: 3530 Comm: syzkaller617982 Not tainted 4.4.113-gef588ef #26 [ 30.080819] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.090140] task: ffff8801cf058000 task.stack: ffff8801cec30000 [ 30.096162] RIP: 0010:[] [] dump_page_badflags+0x4/0x250 [ 30.104914] RSP: 0018:ffff880100000000 EFLAGS: 00010046 [ 30.110328] RAX: ffff8801cf058000 RBX: ffffea0002ca9d00 RCX: ffffffff8148f8d0 [ 30.117566] RDX: 0000000000000000 RSI: ffffffff838a8de0 RDI: ffffea0002ca9d00 [ 30.124803] RBP: ffff880100000000 R08: 0000000000000001 R09: 0000000000000000 [ 30.132042] R10: 0000000000000002 R11: fffffbfff0ad7e26 R12: 0000000000000000 [ 30.139277] R13: ffffffff838a8de0 R14: 0000000000000000 R15: 0000000000000000 [ 30.146518] FS: 0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000f774eb40 [ 30.154711] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 [ 30.160559] CR2: ffff8800fffffff8 CR3: 00000000b4400000 CR4: 0000000000160670 [ 30.167801] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.175039] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.182277] Stack: [ 30.184390] [ 30.185984] Call Trace: [ 30.188535] [ 30.190564] Code: e8 82 df 06 00 e9 83 fd ff ff e8 78 df 06 00 e9 50 fd ff ff e8 6e df 06 00 e9 1d fd ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 <41> 57 41 56 41 55 49 89 f5 41 54 49 89 d4 53 48 89 fb 48 83 ec [ 30.217430] Kernel panic - not syncing: Machine halted. [ 30.222763] CPU: 1 PID: 3530 Comm: syzkaller617982 Not tainted 4.4.113-gef588ef #26 [ 30.230524] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.239846] 0000000000000000 186d8abf915aa594 ffff8801db30ce38 ffffffff81d0278d [ 30.247821] ffffffff83837200 ffff8801db30cf10 ffffffff83808040 ffff880100000000 [ 30.255774] 0000000000000000 ffff8801db30cf00 ffffffff81419b6a 0000000041b58ab3 [ 30.263735] Call Trace: [ 30.266284] <#DF> [] dump_stack+0xc1/0x124 [ 30.272346] [] panic+0x1aa/0x388 [ 30.277331] [] ? percpu_up_read.constprop.45+0xe1/0xe1 [ 30.284227] [] ? vprintk_emit+0x242/0x850 [ 30.289995] [] ? dump_page_badflags+0x19/0x250 [ 30.296195] [] ? vprintk_emit+0x242/0x850 [ 30.301961] [] df_debug+0x2d/0x30 [ 30.307031] [] do_double_fault+0x10b/0x210 [ 30.312883] [] double_fault+0x2d/0x40 [ 30.318301] [] ? dump_page_badflags+0x180/0x250 [ 30.324589] [] ? dump_page_badflags+0x4/0x250 [ 30.330696] <> [ 30.334169] Dumping ftrace buffer: [ 30.337999] (ftrace buffer empty) [ 30.341676] Kernel Offset: disabled [ 30.345277] Rebooting in 86400 seconds..