[....] Starting OpenBSD Secure Shell server: sshd[ 11.990372] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 41.732227] random: sshd: uninitialized urandom read (32 bytes read) [ 42.089620] audit: type=1400 audit(1569070573.430:6): avc: denied { map } for pid=1766 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 [ 42.124310] random: sshd: uninitialized urandom read (32 bytes read) [ 42.665296] random: sshd: uninitialized urandom read (32 bytes read) [ 42.823038] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.129' (ECDSA) to the list of known hosts. [ 48.269919] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 48.363891] audit: type=1400 audit(1569070579.710:7): avc: denied { map } for pid=1784 comm="syz-executor766" path="/root/syz-executor766041473" 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 [ 48.368015] ================================================================== [ 48.397458] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 48.404193] Read of size 2 at addr ffff8881d007ef30 by task syz-executor766/1784 [ 48.411719] [ 48.413339] CPU: 1 PID: 1784 Comm: syz-executor766 Not tainted 4.14.145+ #0 [ 48.420424] Call Trace: [ 48.422997] dump_stack+0xca/0x134 [ 48.426526] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.430921] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.435309] print_address_description+0x60/0x226 [ 48.440130] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.444514] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.448898] __kasan_report.cold+0x1a/0x41 [ 48.453111] ? kvm_guest_cpu_init+0x220/0x220 [ 48.457593] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.461994] tcp_init_tso_segs+0x19d/0x1f0 [ 48.466213] ? tcp_tso_segs+0x7b/0x1c0 [ 48.470089] tcp_write_xmit+0x15a/0x4730 [ 48.474141] ? ip6_mtu+0x206/0x330 [ 48.477662] ? lock_downgrade+0x5d0/0x5d0 [ 48.481786] ? lock_acquire+0x12b/0x360 [ 48.485755] __tcp_push_pending_frames+0xa0/0x230 [ 48.490575] tcp_send_fin+0x154/0xbc0 [ 48.494357] tcp_close+0xc62/0xf40 [ 48.497874] ? lock_acquire+0x12b/0x360 [ 48.501928] ? __sock_release+0x86/0x2c0 [ 48.505983] inet_release+0xe9/0x1c0 [ 48.509697] inet6_release+0x4c/0x70 [ 48.513403] __sock_release+0xd2/0x2c0 [ 48.517270] ? __sock_release+0x2c0/0x2c0 [ 48.521403] sock_close+0x15/0x20 [ 48.524838] __fput+0x25e/0x710 [ 48.528099] task_work_run+0x125/0x1a0 [ 48.531970] do_exit+0x9cb/0x2a20 [ 48.535416] ? mm_update_next_owner+0x610/0x610 [ 48.540069] ? SyS_socket+0x143/0x1e0 [ 48.543862] do_group_exit+0x100/0x2e0 [ 48.547729] SyS_exit_group+0x19/0x20 [ 48.551508] ? do_group_exit+0x2e0/0x2e0 [ 48.555552] do_syscall_64+0x19b/0x520 [ 48.559422] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.564589] RIP: 0033:0x43ee88 [ 48.567868] RSP: 002b:00007ffcfb990ab8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.575553] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 48.582800] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 48.590050] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.597388] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 48.604634] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 48.611889] [ 48.613503] Allocated by task 1784: [ 48.617111] __kasan_kmalloc.part.0+0x53/0xc0 [ 48.621591] kmem_cache_alloc+0xee/0x360 [ 48.625626] __alloc_skb+0xea/0x5c0 [ 48.629226] sk_stream_alloc_skb+0xf4/0x8a0 [ 48.633542] tcp_sendmsg_locked+0xf11/0x2f50 [ 48.638202] tcp_sendmsg+0x2b/0x40 [ 48.641722] inet_sendmsg+0x15b/0x520 [ 48.645499] sock_sendmsg+0xb7/0x100 [ 48.649222] SyS_sendto+0x1de/0x2f0 [ 48.652846] do_syscall_64+0x19b/0x520 [ 48.656719] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.661885] 0xffffffffffffffff [ 48.665139] [ 48.666742] Freed by task 1784: [ 48.669995] __kasan_slab_free+0x164/0x210 [ 48.674207] kmem_cache_free+0xd7/0x3b0 [ 48.678264] kfree_skbmem+0x84/0x110 [ 48.681955] tcp_remove_empty_skb+0x264/0x320 [ 48.686428] tcp_sendmsg_locked+0x1c09/0x2f50 [ 48.690919] tcp_sendmsg+0x2b/0x40 [ 48.694443] inet_sendmsg+0x15b/0x520 [ 48.698229] sock_sendmsg+0xb7/0x100 [ 48.701919] SyS_sendto+0x1de/0x2f0 [ 48.705527] do_syscall_64+0x19b/0x520 [ 48.709526] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.714703] 0xffffffffffffffff [ 48.717968] [ 48.719576] The buggy address belongs to the object at ffff8881d007ef00 [ 48.719576] which belongs to the cache skbuff_fclone_cache of size 456 [ 48.732918] The buggy address is located 48 bytes inside of [ 48.732918] 456-byte region [ffff8881d007ef00, ffff8881d007f0c8) [ 48.744774] The buggy address belongs to the page: [ 48.749687] page:ffffea0007401f80 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 48.759639] flags: 0x4000000000010200(slab|head) [ 48.764380] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 48.772257] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 48.780120] page dumped because: kasan: bad access detected [ 48.785805] [ 48.787453] Memory state around the buggy address: [ 48.792359] ffff8881d007ee00: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 48.799717] ffff8881d007ee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 48.807054] >ffff8881d007ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.814475] ^ [ 48.819379] ffff8881d007ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.826720] ffff8881d007f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.834068] ================================================================== [ 48.841402] Disabling lock debugging due to kernel taint [ 48.847817] Kernel panic - not syncing: panic_on_warn set ... [ 48.847817] [ 48.855206] CPU: 1 PID: 1784 Comm: syz-executor766 Tainted: G B 4.14.145+ #0 [ 48.863496] Call Trace: [ 48.866069] dump_stack+0xca/0x134 [ 48.869587] panic+0x1ea/0x3d3 [ 48.872758] ? add_taint.cold+0x16/0x16 [ 48.876711] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.881096] ? ___preempt_schedule+0x16/0x18 [ 48.885483] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.889866] end_report+0x43/0x49 [ 48.893295] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.897689] __kasan_report.cold+0xd/0x41 [ 48.901819] ? kvm_guest_cpu_init+0x220/0x220 [ 48.906303] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.910686] tcp_init_tso_segs+0x19d/0x1f0 [ 48.914893] ? tcp_tso_segs+0x7b/0x1c0 [ 48.918756] tcp_write_xmit+0x15a/0x4730 [ 48.922798] ? ip6_mtu+0x206/0x330 [ 48.926315] ? lock_downgrade+0x5d0/0x5d0 [ 48.930461] ? lock_acquire+0x12b/0x360 [ 48.934426] __tcp_push_pending_frames+0xa0/0x230 [ 48.939265] tcp_send_fin+0x154/0xbc0 [ 48.943052] tcp_close+0xc62/0xf40 [ 48.946578] ? lock_acquire+0x12b/0x360 [ 48.950530] ? __sock_release+0x86/0x2c0 [ 48.954572] inet_release+0xe9/0x1c0 [ 48.958263] inet6_release+0x4c/0x70 [ 48.961953] __sock_release+0xd2/0x2c0 [ 48.965814] ? __sock_release+0x2c0/0x2c0 [ 48.969934] sock_close+0x15/0x20 [ 48.973364] __fput+0x25e/0x710 [ 48.976620] task_work_run+0x125/0x1a0 [ 48.980494] do_exit+0x9cb/0x2a20 [ 48.983935] ? mm_update_next_owner+0x610/0x610 [ 48.988586] ? SyS_socket+0x143/0x1e0 [ 48.992361] do_group_exit+0x100/0x2e0 [ 48.996232] SyS_exit_group+0x19/0x20 [ 49.000015] ? do_group_exit+0x2e0/0x2e0 [ 49.004057] do_syscall_64+0x19b/0x520 [ 49.007924] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.013099] RIP: 0033:0x43ee88 [ 49.016263] RSP: 002b:00007ffcfb990ab8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 49.024032] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 49.031277] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 49.038522] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 49.045871] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 49.053117] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 49.061565] Kernel Offset: 0x28a00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 49.072479] Rebooting in 86400 seconds..