[....] Starting file context maintaining daemon: restorecond[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 39.589503] random: sshd: uninitialized urandom read (32 bytes read) [ 40.105671] audit: type=1400 audit(1569065971.336:6): avc: denied { map } for pid=1778 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 [ 40.137891] random: sshd: uninitialized urandom read (32 bytes read) [ 40.650990] random: sshd: uninitialized urandom read (32 bytes read) [ 40.803833] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.26' (ECDSA) to the list of known hosts. [ 46.331364] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 46.424388] audit: type=1400 audit(1569065977.656:7): avc: denied { map } for pid=1796 comm="syz-executor164" path="/root/syz-executor164396712" 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 [ 46.429101] ================================================================== [ 46.458679] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 46.465431] Read of size 2 at addr ffff8881cfe26030 by task syz-executor164/1796 [ 46.473011] [ 46.474623] CPU: 0 PID: 1796 Comm: syz-executor164 Not tainted 4.14.145+ #0 [ 46.481705] Call Trace: [ 46.484289] dump_stack+0xca/0x134 [ 46.487815] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.492208] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.496612] print_address_description+0x60/0x226 [ 46.501440] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.505834] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.510226] __kasan_report.cold+0x1a/0x41 [ 46.514447] ? kvm_guest_cpu_init+0x220/0x220 [ 46.519141] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.523709] tcp_init_tso_segs+0x19d/0x1f0 [ 46.528061] ? tcp_tso_segs+0x7b/0x1c0 [ 46.531951] tcp_write_xmit+0x15a/0x4730 [ 46.536005] ? ip6_mtu+0x206/0x330 [ 46.539542] ? lock_downgrade+0x5d0/0x5d0 [ 46.543684] ? lock_acquire+0x12b/0x360 [ 46.547662] __tcp_push_pending_frames+0xa0/0x230 [ 46.552679] tcp_send_fin+0x154/0xbc0 [ 46.556474] tcp_close+0xc62/0xf40 [ 46.560158] ? lock_acquire+0x12b/0x360 [ 46.564127] ? __sock_release+0x86/0x2c0 [ 46.568193] inet_release+0xe9/0x1c0 [ 46.571916] inet6_release+0x4c/0x70 [ 46.575657] __sock_release+0xd2/0x2c0 [ 46.579528] ? __sock_release+0x2c0/0x2c0 [ 46.583672] sock_close+0x15/0x20 [ 46.587115] __fput+0x25e/0x710 [ 46.590385] task_work_run+0x125/0x1a0 [ 46.594260] do_exit+0x9cb/0x2a20 [ 46.597702] ? mm_update_next_owner+0x610/0x610 [ 46.602364] ? SyS_socket+0x143/0x1e0 [ 46.606155] do_group_exit+0x100/0x2e0 [ 46.610064] SyS_exit_group+0x19/0x20 [ 46.613947] ? do_group_exit+0x2e0/0x2e0 [ 46.617991] do_syscall_64+0x19b/0x520 [ 46.621872] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.627147] RIP: 0033:0x43ee88 [ 46.630335] RSP: 002b:00007ffdc2cae988 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 46.638040] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 46.645384] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 46.652926] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 46.660183] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 46.667441] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 46.674709] [ 46.676322] Allocated by task 1796: [ 46.679948] __kasan_kmalloc.part.0+0x53/0xc0 [ 46.684444] kmem_cache_alloc+0xee/0x360 [ 46.688509] __alloc_skb+0xea/0x5c0 [ 46.692126] sk_stream_alloc_skb+0xf4/0x8a0 [ 46.696443] tcp_sendmsg_locked+0xf11/0x2f50 [ 46.701016] tcp_sendmsg+0x2b/0x40 [ 46.704549] inet_sendmsg+0x15b/0x520 [ 46.708357] sock_sendmsg+0xb7/0x100 [ 46.712074] SyS_sendto+0x1de/0x2f0 [ 46.715860] do_syscall_64+0x19b/0x520 [ 46.719742] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.725055] 0xffffffffffffffff [ 46.728366] [ 46.729972] Freed by task 1796: [ 46.733242] __kasan_slab_free+0x164/0x210 [ 46.737472] kmem_cache_free+0xd7/0x3b0 [ 46.741433] kfree_skbmem+0x84/0x110 [ 46.745148] tcp_remove_empty_skb+0x264/0x320 [ 46.749625] tcp_sendmsg_locked+0x1c09/0x2f50 [ 46.754195] tcp_sendmsg+0x2b/0x40 [ 46.757736] inet_sendmsg+0x15b/0x520 [ 46.761523] sock_sendmsg+0xb7/0x100 [ 46.765218] SyS_sendto+0x1de/0x2f0 [ 46.768826] do_syscall_64+0x19b/0x520 [ 46.772719] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 46.777978] 0xffffffffffffffff [ 46.781237] [ 46.782863] The buggy address belongs to the object at ffff8881cfe26000 [ 46.782863] which belongs to the cache skbuff_fclone_cache of size 456 [ 46.796208] The buggy address is located 48 bytes inside of [ 46.796208] 456-byte region [ffff8881cfe26000, ffff8881cfe261c8) [ 46.808067] The buggy address belongs to the page: [ 46.812985] page:ffffea00073f8980 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 46.822941] flags: 0x4000000000010200(slab|head) [ 46.827939] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 46.835825] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 46.843726] page dumped because: kasan: bad access detected [ 46.849684] [ 46.851299] Memory state around the buggy address: [ 46.856234] ffff8881cfe25f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 46.863925] ffff8881cfe25f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 46.871267] >ffff8881cfe26000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.878604] ^ [ 46.883618] ffff8881cfe26080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.890963] ffff8881cfe26100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 46.898326] ================================================================== [ 46.905675] Disabling lock debugging due to kernel taint [ 46.911195] Kernel panic - not syncing: panic_on_warn set ... [ 46.911195] [ 46.918648] CPU: 0 PID: 1796 Comm: syz-executor164 Tainted: G B 4.14.145+ #0 [ 46.926945] Call Trace: [ 46.929532] dump_stack+0xca/0x134 [ 46.933259] panic+0x1ea/0x3d3 [ 46.936516] ? add_taint.cold+0x16/0x16 [ 46.940489] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.944890] ? ___preempt_schedule+0x16/0x18 [ 46.949527] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.953958] end_report+0x43/0x49 [ 46.957403] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.961968] __kasan_report.cold+0xd/0x41 [ 46.966205] ? kvm_guest_cpu_init+0x220/0x220 [ 46.971058] ? tcp_init_tso_segs+0x19d/0x1f0 [ 46.975462] tcp_init_tso_segs+0x19d/0x1f0 [ 46.979698] ? tcp_tso_segs+0x7b/0x1c0 [ 46.983573] tcp_write_xmit+0x15a/0x4730 [ 46.987622] ? ip6_mtu+0x206/0x330 [ 46.991160] ? lock_downgrade+0x5d0/0x5d0 [ 46.995301] ? lock_acquire+0x12b/0x360 [ 46.999264] __tcp_push_pending_frames+0xa0/0x230 [ 47.004110] tcp_send_fin+0x154/0xbc0 [ 47.007969] tcp_close+0xc62/0xf40 [ 47.011558] ? lock_acquire+0x12b/0x360 [ 47.015526] ? __sock_release+0x86/0x2c0 [ 47.019579] inet_release+0xe9/0x1c0 [ 47.023289] inet6_release+0x4c/0x70 [ 47.027059] __sock_release+0xd2/0x2c0 [ 47.030932] ? __sock_release+0x2c0/0x2c0 [ 47.035079] sock_close+0x15/0x20 [ 47.038534] __fput+0x25e/0x710 [ 47.041801] task_work_run+0x125/0x1a0 [ 47.045676] do_exit+0x9cb/0x2a20 [ 47.049214] ? mm_update_next_owner+0x610/0x610 [ 47.053882] ? SyS_socket+0x143/0x1e0 [ 47.057692] do_group_exit+0x100/0x2e0 [ 47.061732] SyS_exit_group+0x19/0x20 [ 47.065531] ? do_group_exit+0x2e0/0x2e0 [ 47.069578] do_syscall_64+0x19b/0x520 [ 47.073478] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.078714] RIP: 0033:0x43ee88 [ 47.081902] RSP: 002b:00007ffdc2cae988 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 47.089597] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 47.096852] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 47.104117] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 47.111367] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 47.118628] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 47.127223] Kernel Offset: 0x19600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 47.138342] Rebooting in 86400 seconds..