[....] Starting OpenBSD Secure Shell server: sshd[ 12.326322] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 31.554883] random: sshd: uninitialized urandom read (32 bytes read) [ 32.005315] audit: type=1400 audit(1569061727.227:6): avc: denied { map } for pid=1773 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 [ 32.055150] random: sshd: uninitialized urandom read (32 bytes read) [ 32.663116] random: sshd: uninitialized urandom read (32 bytes read) [ 32.838497] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.242' (ECDSA) to the list of known hosts. [ 38.441399] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 38.533430] audit: type=1400 audit(1569061733.757:7): avc: denied { map } for pid=1791 comm="syz-executor746" path="/root/syz-executor746120714" 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 [ 38.537494] ================================================================== [ 38.567417] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 38.575401] Read of size 2 at addr ffff8881d6e936b0 by task syz-executor746/1791 [ 38.583004] [ 38.584617] CPU: 0 PID: 1791 Comm: syz-executor746 Not tainted 4.14.145+ #0 [ 38.591698] Call Trace: [ 38.594277] dump_stack+0xca/0x134 [ 38.597800] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.602389] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.606915] print_address_description+0x60/0x226 [ 38.611744] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.616584] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.620980] __kasan_report.cold+0x1a/0x41 [ 38.625205] ? kvm_guest_cpu_init+0x220/0x220 [ 38.630032] ? tcp_init_tso_segs+0x19d/0x1f0 [ 38.634727] tcp_init_tso_segs+0x19d/0x1f0 [ 38.638973] ? tcp_tso_segs+0x7b/0x1c0 [ 38.642938] tcp_write_xmit+0x15a/0x4730 [ 38.647003] ? ip6_mtu+0x206/0x330 [ 38.650617] ? lock_downgrade+0x5d0/0x5d0 [ 38.654754] ? lock_acquire+0x12b/0x360 [ 38.658741] __tcp_push_pending_frames+0xa0/0x230 [ 38.663572] tcp_send_fin+0x154/0xbc0 [ 38.667381] tcp_close+0xc62/0xf40 [ 38.671006] ? lock_acquire+0x12b/0x360 [ 38.674965] ? __sock_release+0x86/0x2c0 [ 38.679022] inet_release+0xe9/0x1c0 [ 38.682743] inet6_release+0x4c/0x70 [ 38.686444] __sock_release+0xd2/0x2c0 [ 38.690315] ? __sock_release+0x2c0/0x2c0 [ 38.694448] sock_close+0x15/0x20 [ 38.697928] __fput+0x25e/0x710 [ 38.701198] task_work_run+0x125/0x1a0 [ 38.705156] do_exit+0x9cb/0x2a20 [ 38.708609] ? mm_update_next_owner+0x610/0x610 [ 38.713289] ? SyS_socket+0x143/0x1e0 [ 38.717097] do_group_exit+0x100/0x2e0 [ 38.720984] SyS_exit_group+0x19/0x20 [ 38.724766] ? do_group_exit+0x2e0/0x2e0 [ 38.728994] do_syscall_64+0x19b/0x520 [ 38.732889] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.738061] RIP: 0033:0x43ee88 [ 38.741230] RSP: 002b:00007ffe66a55288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 38.748949] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 38.756578] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 38.763949] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 38.771302] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 38.778665] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 38.786214] [ 38.787825] Allocated by task 1791: [ 38.791460] __kasan_kmalloc.part.0+0x53/0xc0 [ 38.796166] kmem_cache_alloc+0xee/0x360 [ 38.800746] __alloc_skb+0xea/0x5c0 [ 38.804373] sk_stream_alloc_skb+0xf4/0x8a0 [ 38.808685] tcp_sendmsg_locked+0xf11/0x2f50 [ 38.813105] tcp_sendmsg+0x2b/0x40 [ 38.816629] inet_sendmsg+0x15b/0x520 [ 38.820499] sock_sendmsg+0xb7/0x100 [ 38.824193] SyS_sendto+0x1de/0x2f0 [ 38.827802] do_syscall_64+0x19b/0x520 [ 38.831694] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.836865] 0xffffffffffffffff [ 38.840141] [ 38.841752] Freed by task 1791: [ 38.845068] __kasan_slab_free+0x164/0x210 [ 38.849388] kmem_cache_free+0xd7/0x3b0 [ 38.853361] kfree_skbmem+0x84/0x110 [ 38.857061] tcp_remove_empty_skb+0x264/0x320 [ 38.861544] tcp_sendmsg_locked+0x1c09/0x2f50 [ 38.866019] tcp_sendmsg+0x2b/0x40 [ 38.870070] inet_sendmsg+0x15b/0x520 [ 38.873861] sock_sendmsg+0xb7/0x100 [ 38.877554] SyS_sendto+0x1de/0x2f0 [ 38.881162] do_syscall_64+0x19b/0x520 [ 38.885031] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 38.890204] 0xffffffffffffffff [ 38.894251] [ 38.895861] The buggy address belongs to the object at ffff8881d6e93680 [ 38.895861] which belongs to the cache skbuff_fclone_cache of size 456 [ 38.909462] The buggy address is located 48 bytes inside of [ 38.909462] 456-byte region [ffff8881d6e93680, ffff8881d6e93848) [ 38.921237] The buggy address belongs to the page: [ 38.926161] page:ffffea00075ba480 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 38.937409] flags: 0x4000000000010200(slab|head) [ 38.942240] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 38.950118] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 38.958176] page dumped because: kasan: bad access detected [ 38.963886] [ 38.965492] Memory state around the buggy address: [ 38.970410] ffff8881d6e93580: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 38.977765] ffff8881d6e93600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 38.985347] >ffff8881d6e93680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 38.992696] ^ [ 38.997612] ffff8881d6e93700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.005049] ffff8881d6e93780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 39.012557] ================================================================== [ 39.020692] Disabling lock debugging due to kernel taint [ 39.026199] Kernel panic - not syncing: panic_on_warn set ... [ 39.026199] [ 39.033564] CPU: 0 PID: 1791 Comm: syz-executor746 Tainted: G B 4.14.145+ #0 [ 39.042291] Call Trace: [ 39.044957] dump_stack+0xca/0x134 [ 39.048478] panic+0x1ea/0x3d3 [ 39.051654] ? add_taint.cold+0x16/0x16 [ 39.055698] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.060085] ? ___preempt_schedule+0x16/0x18 [ 39.064789] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.069193] end_report+0x43/0x49 [ 39.072648] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.077112] __kasan_report.cold+0xd/0x41 [ 39.081245] ? kvm_guest_cpu_init+0x220/0x220 [ 39.085718] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.090116] tcp_init_tso_segs+0x19d/0x1f0 [ 39.094340] ? tcp_tso_segs+0x7b/0x1c0 [ 39.098306] tcp_write_xmit+0x15a/0x4730 [ 39.102538] ? ip6_mtu+0x206/0x330 [ 39.106430] ? lock_downgrade+0x5d0/0x5d0 [ 39.110556] ? lock_acquire+0x12b/0x360 [ 39.114524] __tcp_push_pending_frames+0xa0/0x230 [ 39.119952] tcp_send_fin+0x154/0xbc0 [ 39.123737] tcp_close+0xc62/0xf40 [ 39.127255] ? lock_acquire+0x12b/0x360 [ 39.131215] ? __sock_release+0x86/0x2c0 [ 39.135257] inet_release+0xe9/0x1c0 [ 39.138954] inet6_release+0x4c/0x70 [ 39.142646] __sock_release+0xd2/0x2c0 [ 39.146637] ? __sock_release+0x2c0/0x2c0 [ 39.151196] sock_close+0x15/0x20 [ 39.154628] __fput+0x25e/0x710 [ 39.158071] task_work_run+0x125/0x1a0 [ 39.162065] do_exit+0x9cb/0x2a20 [ 39.166358] ? mm_update_next_owner+0x610/0x610 [ 39.171028] ? SyS_socket+0x143/0x1e0 [ 39.174824] do_group_exit+0x100/0x2e0 [ 39.179041] SyS_exit_group+0x19/0x20 [ 39.182831] ? do_group_exit+0x2e0/0x2e0 [ 39.186868] do_syscall_64+0x19b/0x520 [ 39.190753] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.195923] RIP: 0033:0x43ee88 [ 39.199089] RSP: 002b:00007ffe66a55288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.206874] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 39.214123] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.221386] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 39.229358] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 39.236806] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 39.245193] Kernel Offset: 0x20600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 39.256394] Rebooting in 86400 seconds..