[....] 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: [ 31.083797] random: sshd: uninitialized urandom read (32 bytes read) [ 31.363424] audit: type=1400 audit(1569022040.637:6): avc: denied { map } for pid=1777 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 [ 31.415629] random: sshd: uninitialized urandom read (32 bytes read) [ 31.939079] random: sshd: uninitialized urandom read (32 bytes read) [ 49.638529] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.166' (ECDSA) to the list of known hosts. [ 55.126700] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 55.224535] audit: type=1400 audit(1569022064.497:7): avc: denied { map } for pid=1805 comm="syz-executor254" path="/root/syz-executor254782006" 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 [ 55.234600] ================================================================== [ 55.258333] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 55.265340] Read of size 2 at addr ffff8881da223430 by task syz-executor254/1805 [ 55.272876] [ 55.274490] CPU: 1 PID: 1805 Comm: syz-executor254 Not tainted 4.14.145+ #0 [ 55.281570] Call Trace: [ 55.284174] dump_stack+0xca/0x134 [ 55.287699] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.292130] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.296634] print_address_description+0x60/0x226 [ 55.301468] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.305878] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.310283] __kasan_report.cold+0x1a/0x41 [ 55.314508] ? kvm_guest_cpu_init+0x220/0x220 [ 55.318987] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.323386] tcp_init_tso_segs+0x19d/0x1f0 [ 55.327603] ? tcp_tso_segs+0x7b/0x1c0 [ 55.331479] tcp_write_xmit+0x15a/0x4730 [ 55.335545] ? ip6_mtu+0x206/0x330 [ 55.339069] ? lock_downgrade+0x5d0/0x5d0 [ 55.343212] ? lock_acquire+0x12b/0x360 [ 55.347181] __tcp_push_pending_frames+0xa0/0x230 [ 55.352011] tcp_send_fin+0x154/0xbc0 [ 55.355815] tcp_close+0xc62/0xf40 [ 55.359341] ? lock_acquire+0x12b/0x360 [ 55.363371] ? __sock_release+0x86/0x2c0 [ 55.367423] inet_release+0xe9/0x1c0 [ 55.371130] inet6_release+0x4c/0x70 [ 55.374854] __sock_release+0xd2/0x2c0 [ 55.378730] ? __sock_release+0x2c0/0x2c0 [ 55.382865] sock_close+0x15/0x20 [ 55.386307] __fput+0x25e/0x710 [ 55.389574] task_work_run+0x125/0x1a0 [ 55.393468] do_exit+0x9cb/0x2a20 [ 55.396912] ? mm_update_next_owner+0x610/0x610 [ 55.401591] do_group_exit+0x100/0x2e0 [ 55.405465] SyS_exit_group+0x19/0x20 [ 55.409262] ? do_group_exit+0x2e0/0x2e0 [ 55.413308] do_syscall_64+0x19b/0x520 [ 55.417188] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 55.422364] RIP: 0033:0x43ee78 [ 55.425539] RSP: 002b:00007ffe6c900328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 55.433253] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee78 [ 55.440527] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 55.448782] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 55.456051] R10: 0000000020000008 R11: 0000000000000246 R12: 0000000000000001 [ 55.463425] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 55.470694] [ 55.472305] Allocated by task 1805: [ 55.475932] __kasan_kmalloc.part.0+0x53/0xc0 [ 55.480427] kmem_cache_alloc+0xee/0x360 [ 55.484490] __alloc_skb+0xea/0x5c0 [ 55.488115] sk_stream_alloc_skb+0xf4/0x8a0 [ 55.492434] tcp_sendmsg_locked+0xf11/0x2f50 [ 55.496830] tcp_sendmsg+0x2b/0x40 [ 55.500358] inet_sendmsg+0x15b/0x520 [ 55.504260] sock_sendmsg+0xb7/0x100 [ 55.507963] SyS_sendto+0x1de/0x2f0 [ 55.511578] do_syscall_64+0x19b/0x520 [ 55.515632] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 55.520809] 0xffffffffffffffff [ 55.524089] [ 55.525696] Freed by task 1805: [ 55.528960] __kasan_slab_free+0x164/0x210 [ 55.533178] kmem_cache_free+0xd7/0x3b0 [ 55.537157] kfree_skbmem+0x84/0x110 [ 55.540866] tcp_remove_empty_skb+0x264/0x320 [ 55.545341] tcp_sendmsg_locked+0x1c09/0x2f50 [ 55.549857] tcp_sendmsg+0x2b/0x40 [ 55.553392] inet_sendmsg+0x15b/0x520 [ 55.557177] sock_sendmsg+0xb7/0x100 [ 55.560873] SyS_sendto+0x1de/0x2f0 [ 55.564485] do_syscall_64+0x19b/0x520 [ 55.568379] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 55.573548] 0xffffffffffffffff [ 55.576806] [ 55.578472] The buggy address belongs to the object at ffff8881da223400 [ 55.578472] which belongs to the cache skbuff_fclone_cache of size 456 [ 55.591809] The buggy address is located 48 bytes inside of [ 55.591809] 456-byte region [ffff8881da223400, ffff8881da2235c8) [ 55.603596] The buggy address belongs to the page: [ 55.608530] page:ffffea0007688880 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 55.618594] flags: 0x4000000000010200(slab|head) [ 55.623338] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 55.631207] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 55.639069] page dumped because: kasan: bad access detected [ 55.644761] [ 55.646366] Memory state around the buggy address: [ 55.651297] ffff8881da223300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 55.658665] ffff8881da223380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 55.666008] >ffff8881da223400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 55.673349] ^ [ 55.678259] ffff8881da223480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 55.685617] ffff8881da223500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 55.692958] ================================================================== [ 55.700302] Disabling lock debugging due to kernel taint [ 55.706974] Kernel panic - not syncing: panic_on_warn set ... [ 55.706974] [ 55.714367] CPU: 1 PID: 1805 Comm: syz-executor254 Tainted: G B 4.14.145+ #0 [ 55.722661] Call Trace: [ 55.725236] dump_stack+0xca/0x134 [ 55.728760] panic+0x1ea/0x3d3 [ 55.731949] ? add_taint.cold+0x16/0x16 [ 55.735910] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.740312] ? ___preempt_schedule+0x16/0x18 [ 55.744706] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.749121] end_report+0x43/0x49 [ 55.752572] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.756984] __kasan_report.cold+0xd/0x41 [ 55.761118] ? kvm_guest_cpu_init+0x220/0x220 [ 55.765613] ? tcp_init_tso_segs+0x19d/0x1f0 [ 55.770046] tcp_init_tso_segs+0x19d/0x1f0 [ 55.774276] ? tcp_tso_segs+0x7b/0x1c0 [ 55.778148] tcp_write_xmit+0x15a/0x4730 [ 55.782197] ? ip6_mtu+0x206/0x330 [ 55.785744] ? lock_downgrade+0x5d0/0x5d0 [ 55.790034] ? lock_acquire+0x12b/0x360 [ 55.794044] __tcp_push_pending_frames+0xa0/0x230 [ 55.798885] tcp_send_fin+0x154/0xbc0 [ 55.802675] tcp_close+0xc62/0xf40 [ 55.806215] ? lock_acquire+0x12b/0x360 [ 55.810185] ? __sock_release+0x86/0x2c0 [ 55.814312] inet_release+0xe9/0x1c0 [ 55.818015] inet6_release+0x4c/0x70 [ 55.821727] __sock_release+0xd2/0x2c0 [ 55.825624] ? __sock_release+0x2c0/0x2c0 [ 55.829775] sock_close+0x15/0x20 [ 55.833212] __fput+0x25e/0x710 [ 55.836480] task_work_run+0x125/0x1a0 [ 55.840365] do_exit+0x9cb/0x2a20 [ 55.843968] ? mm_update_next_owner+0x610/0x610 [ 55.848648] do_group_exit+0x100/0x2e0 [ 55.852536] SyS_exit_group+0x19/0x20 [ 55.856885] ? do_group_exit+0x2e0/0x2e0 [ 55.860933] do_syscall_64+0x19b/0x520 [ 55.865021] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 55.870202] RIP: 0033:0x43ee78 [ 55.873374] RSP: 002b:00007ffe6c900328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 55.881096] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee78 [ 55.888514] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 55.895774] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 55.903025] R10: 0000000020000008 R11: 0000000000000246 R12: 0000000000000001 [ 55.910279] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 55.918424] Kernel Offset: 0x26e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 55.929345] Rebooting in 86400 seconds..