[....] 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: [ 25.326417] random: sshd: uninitialized urandom read (32 bytes read) [ 25.656293] audit: type=1400 audit(1569021148.003:6): avc: denied { map } for pid=1769 comm="bash" path="/bin/bash" dev="sda1" ino=1457 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 [ 25.701849] random: sshd: uninitialized urandom read (32 bytes read) [ 26.185186] random: sshd: uninitialized urandom read (32 bytes read) [ 26.351997] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.209' (ECDSA) to the list of known hosts. [ 31.746687] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 31.841063] audit: type=1400 audit(1569021154.193:7): avc: denied { map } for pid=1787 comm="syz-executor054" path="/root/syz-executor054380694" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 [ 31.871631] ================================================================== [ 31.879167] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 31.885912] Read of size 2 at addr ffff8881cf96c530 by task syz-executor054/1787 [ 31.893519] [ 31.895127] CPU: 0 PID: 1787 Comm: syz-executor054 Not tainted 4.14.145+ #0 [ 31.902293] Call Trace: [ 31.904876] dump_stack+0xca/0x134 [ 31.908395] ? tcp_init_tso_segs+0x19d/0x1f0 [ 31.912897] ? tcp_init_tso_segs+0x19d/0x1f0 [ 31.917292] print_address_description+0x60/0x226 [ 31.922125] ? tcp_init_tso_segs+0x19d/0x1f0 [ 31.926518] ? tcp_init_tso_segs+0x19d/0x1f0 [ 31.931082] __kasan_report.cold+0x1a/0x41 [ 31.935295] ? kvm_guest_cpu_init+0x220/0x220 [ 31.939823] ? tcp_init_tso_segs+0x19d/0x1f0 [ 31.944330] tcp_init_tso_segs+0x19d/0x1f0 [ 31.948558] ? tcp_tso_segs+0x7b/0x1c0 [ 31.952437] tcp_write_xmit+0x15a/0x4730 [ 31.956514] ? memset+0x20/0x40 [ 31.959784] __tcp_push_pending_frames+0xa0/0x230 [ 31.964626] tcp_send_fin+0x154/0xbc0 [ 31.968411] tcp_close+0xc62/0xf40 [ 31.971941] inet_release+0xe9/0x1c0 [ 31.975639] __sock_release+0xd2/0x2c0 [ 31.980379] ? __sock_release+0x2c0/0x2c0 [ 31.984507] sock_close+0x15/0x20 [ 31.987950] __fput+0x25e/0x710 [ 31.991231] task_work_run+0x125/0x1a0 [ 31.995115] do_exit+0x9cb/0x2a20 [ 31.998551] ? mm_update_next_owner+0x610/0x610 [ 32.003236] do_group_exit+0x100/0x2e0 [ 32.007119] SyS_exit_group+0x19/0x20 [ 32.010899] ? do_group_exit+0x2e0/0x2e0 [ 32.014953] do_syscall_64+0x19b/0x520 [ 32.018825] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.024026] RIP: 0033:0x43ee08 [ 32.027213] RSP: 002b:00007ffee3172598 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 32.034907] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 32.042171] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 32.049434] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 32.056692] R10: 000000002004073c R11: 0000000000000246 R12: 0000000000000001 [ 32.063969] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 32.071805] [ 32.073439] Allocated by task 1787: [ 32.077055] __kasan_kmalloc.part.0+0x53/0xc0 [ 32.081545] kmem_cache_alloc+0xee/0x360 [ 32.085602] __alloc_skb+0xea/0x5c0 [ 32.089210] sk_stream_alloc_skb+0xf4/0x8a0 [ 32.093513] tcp_sendmsg_locked+0xf11/0x2f50 [ 32.097912] tcp_sendmsg+0x2b/0x40 [ 32.101433] inet_sendmsg+0x15b/0x520 [ 32.105222] sock_sendmsg+0xb7/0x100 [ 32.108912] SyS_sendto+0x1de/0x2f0 [ 32.112615] do_syscall_64+0x19b/0x520 [ 32.116493] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.121662] 0xffffffffffffffff [ 32.124916] [ 32.126607] Freed by task 1787: [ 32.129863] __kasan_slab_free+0x164/0x210 [ 32.134078] kmem_cache_free+0xd7/0x3b0 [ 32.138046] kfree_skbmem+0x84/0x110 [ 32.141806] tcp_remove_empty_skb+0x264/0x320 [ 32.146289] tcp_sendmsg_locked+0x1c09/0x2f50 [ 32.150938] tcp_sendmsg+0x2b/0x40 [ 32.154491] inet_sendmsg+0x15b/0x520 [ 32.158448] sock_sendmsg+0xb7/0x100 [ 32.162153] SyS_sendto+0x1de/0x2f0 [ 32.165849] do_syscall_64+0x19b/0x520 [ 32.169824] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.175053] 0xffffffffffffffff [ 32.178318] [ 32.179928] The buggy address belongs to the object at ffff8881cf96c500 [ 32.179928] which belongs to the cache skbuff_fclone_cache of size 456 [ 32.193263] The buggy address is located 48 bytes inside of [ 32.193263] 456-byte region [ffff8881cf96c500, ffff8881cf96c6c8) [ 32.205226] The buggy address belongs to the page: [ 32.210153] page:ffffea00073e5b00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 32.220134] flags: 0x4000000000010200(slab|head) [ 32.224876] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 32.232738] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 32.240614] page dumped because: kasan: bad access detected [ 32.246314] [ 32.247922] Memory state around the buggy address: [ 32.252829] ffff8881cf96c400: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 32.260180] ffff8881cf96c480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 32.267536] >ffff8881cf96c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.274879] ^ [ 32.279785] ffff8881cf96c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.287217] ffff8881cf96c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 32.294566] ================================================================== [ 32.301919] Disabling lock debugging due to kernel taint [ 32.309405] Kernel panic - not syncing: panic_on_warn set ... [ 32.309405] [ 32.316851] CPU: 0 PID: 1787 Comm: syz-executor054 Tainted: G B 4.14.145+ #0 [ 32.325249] Call Trace: [ 32.327828] dump_stack+0xca/0x134 [ 32.331351] panic+0x1ea/0x3d3 [ 32.334521] ? add_taint.cold+0x16/0x16 [ 32.338498] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.342892] ? ___preempt_schedule+0x16/0x18 [ 32.347283] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.351670] end_report+0x43/0x49 [ 32.355106] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.359496] __kasan_report.cold+0xd/0x41 [ 32.363628] ? kvm_guest_cpu_init+0x220/0x220 [ 32.368114] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.372515] tcp_init_tso_segs+0x19d/0x1f0 [ 32.376736] ? tcp_tso_segs+0x7b/0x1c0 [ 32.380602] tcp_write_xmit+0x15a/0x4730 [ 32.384650] ? memset+0x20/0x40 [ 32.387910] __tcp_push_pending_frames+0xa0/0x230 [ 32.392730] tcp_send_fin+0x154/0xbc0 [ 32.396509] tcp_close+0xc62/0xf40 [ 32.400037] inet_release+0xe9/0x1c0 [ 32.403743] __sock_release+0xd2/0x2c0 [ 32.407868] ? __sock_release+0x2c0/0x2c0 [ 32.411992] sock_close+0x15/0x20 [ 32.415436] __fput+0x25e/0x710 [ 32.418706] task_work_run+0x125/0x1a0 [ 32.422579] do_exit+0x9cb/0x2a20 [ 32.426011] ? mm_update_next_owner+0x610/0x610 [ 32.430664] do_group_exit+0x100/0x2e0 [ 32.434530] SyS_exit_group+0x19/0x20 [ 32.438395] ? do_group_exit+0x2e0/0x2e0 [ 32.442436] do_syscall_64+0x19b/0x520 [ 32.446310] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.451491] RIP: 0033:0x43ee08 [ 32.454658] RSP: 002b:00007ffee3172598 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 32.462344] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 32.469595] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 32.476843] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 32.484091] R10: 000000002004073c R11: 0000000000000246 R12: 0000000000000001 [ 32.491348] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 32.499409] Kernel Offset: 0x7600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 32.510321] Rebooting in 86400 seconds..