[....] 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: [ 26.329878] random: sshd: uninitialized urandom read (32 bytes read) [ 26.701930] audit: type=1400 audit(1569016951.101:6): avc: denied { map } for pid=1764 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 [ 26.746255] random: sshd: uninitialized urandom read (32 bytes read) [ 27.223675] random: sshd: uninitialized urandom read (32 bytes read) [ 42.832396] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.16' (ECDSA) to the list of known hosts. [ 48.282017] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 48.371307] audit: type=1400 audit(1569016972.771:7): avc: denied { map } for pid=1788 comm="syz-executor367" path="/root/syz-executor367422552" 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 [ 48.376029] ================================================================== [ 48.404923] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 48.411656] Read of size 2 at addr ffff8881ce9ca2b0 by task syz-executor367/1789 [ 48.419166] [ 48.420776] CPU: 1 PID: 1789 Comm: syz-executor367 Not tainted 4.14.145+ #0 [ 48.427860] Call Trace: [ 48.430429] dump_stack+0xca/0x134 [ 48.433945] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.438330] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.442715] print_address_description+0x60/0x226 [ 48.447535] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.451921] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.456303] __kasan_report.cold+0x1a/0x41 [ 48.460517] ? kvm_guest_cpu_init+0x220/0x220 [ 48.465000] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.469386] tcp_init_tso_segs+0x19d/0x1f0 [ 48.473597] ? tcp_tso_segs+0x7b/0x1c0 [ 48.477461] tcp_write_xmit+0x15a/0x4730 [ 48.481503] ? ip6_mtu+0x206/0x330 [ 48.485033] ? lock_downgrade+0x5d0/0x5d0 [ 48.489157] ? lock_acquire+0x12b/0x360 [ 48.493116] __tcp_push_pending_frames+0xa0/0x230 [ 48.497935] tcp_send_fin+0x154/0xbc0 [ 48.501717] tcp_close+0xc62/0xf40 [ 48.505232] ? lock_acquire+0x12b/0x360 [ 48.509193] ? __sock_release+0x86/0x2c0 [ 48.513247] inet_release+0xe9/0x1c0 [ 48.516941] inet6_release+0x4c/0x70 [ 48.520633] __sock_release+0xd2/0x2c0 [ 48.524518] ? __sock_release+0x2c0/0x2c0 [ 48.528639] sock_close+0x15/0x20 [ 48.532070] __fput+0x25e/0x710 [ 48.535331] task_work_run+0x125/0x1a0 [ 48.539198] do_exit+0x9cb/0x2a20 [ 48.542632] ? futex_wake+0x15b/0x440 [ 48.546413] ? mm_update_next_owner+0x610/0x610 [ 48.551062] ? get_signal+0x334/0x1cc0 [ 48.554926] ? lock_downgrade+0x5d0/0x5d0 [ 48.559047] ? lock_acquire+0x12b/0x360 [ 48.563010] ? get_signal+0x1e7/0x1cc0 [ 48.566877] do_group_exit+0x100/0x2e0 [ 48.570742] get_signal+0x39f/0x1cc0 [ 48.574444] do_signal+0x96/0x15d0 [ 48.577960] ? inet_sendmsg+0x163/0x520 [ 48.581917] ? fput+0x19/0x150 [ 48.585090] ? setup_sigcontext+0x810/0x810 [ 48.589399] ? SyS_getpeername+0x250/0x250 [ 48.593623] ? SyS_futex+0x1c5/0x2c3 [ 48.597312] ? SyS_futex+0x1cf/0x2c3 [ 48.601005] ? do_futex+0x1980/0x1980 [ 48.604782] ? exit_to_usermode_loop+0xcd/0x160 [ 48.609429] exit_to_usermode_loop+0x11d/0x160 [ 48.613991] do_syscall_64+0x3a3/0x520 [ 48.617859] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.623025] RIP: 0033:0x445899 [ 48.626193] RSP: 002b:00007f39771e5da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 48.633877] RAX: 0000000000000001 RBX: 00000000006dac28 RCX: 0000000000445899 [ 48.641125] RDX: 000000000000001c RSI: 0000000000000081 RDI: 00000000006dac2c [ 48.648371] RBP: 00000000006dac20 R08: 000000000000001c R09: 0000000000000000 [ 48.655615] R10: 0000000020000280 R11: 0000000000000246 R12: 00000000006dac2c [ 48.662862] R13: 0000000000000000 R14: 0000000000000000 R15: 20c49ba5e353f7cf [ 48.670117] [ 48.671722] Allocated by task 1789: [ 48.675326] __kasan_kmalloc.part.0+0x53/0xc0 [ 48.679794] kmem_cache_alloc+0xee/0x360 [ 48.683829] __alloc_skb+0xea/0x5c0 [ 48.687440] sk_stream_alloc_skb+0xf4/0x8a0 [ 48.691736] tcp_sendmsg_locked+0xf11/0x2f50 [ 48.696121] tcp_sendmsg+0x2b/0x40 [ 48.699634] inet_sendmsg+0x15b/0x520 [ 48.703409] sock_sendmsg+0xb7/0x100 [ 48.707109] SyS_sendto+0x1de/0x2f0 [ 48.710714] do_syscall_64+0x19b/0x520 [ 48.714575] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.719757] 0xffffffffffffffff [ 48.723018] [ 48.724627] Freed by task 1789: [ 48.727932] __kasan_slab_free+0x164/0x210 [ 48.732148] kmem_cache_free+0xd7/0x3b0 [ 48.736104] kfree_skbmem+0x84/0x110 [ 48.739795] tcp_remove_empty_skb+0x264/0x320 [ 48.744266] tcp_sendmsg_locked+0x1c09/0x2f50 [ 48.748739] tcp_sendmsg+0x2b/0x40 [ 48.752255] inet_sendmsg+0x15b/0x520 [ 48.756035] sock_sendmsg+0xb7/0x100 [ 48.759724] SyS_sendto+0x1de/0x2f0 [ 48.763341] do_syscall_64+0x19b/0x520 [ 48.767215] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.772380] 0xffffffffffffffff [ 48.775651] [ 48.777255] The buggy address belongs to the object at ffff8881ce9ca280 [ 48.777255] which belongs to the cache skbuff_fclone_cache of size 456 [ 48.790581] The buggy address is located 48 bytes inside of [ 48.790581] 456-byte region [ffff8881ce9ca280, ffff8881ce9ca448) [ 48.802342] The buggy address belongs to the page: [ 48.807252] page:ffffea00073a7280 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 48.817196] flags: 0x4000000000010200(slab|head) [ 48.821944] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 48.829813] raw: dead000000000100 dead000000000200 ffff8881d6770400 0000000000000000 [ 48.837683] page dumped because: kasan: bad access detected [ 48.843364] [ 48.844966] Memory state around the buggy address: [ 48.849868] ffff8881ce9ca180: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 48.857199] ffff8881ce9ca200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 48.864557] >ffff8881ce9ca280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.871891] ^ [ 48.876793] ffff8881ce9ca300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.884126] ffff8881ce9ca380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.891457] ================================================================== [ 48.898791] Disabling lock debugging due to kernel taint [ 48.904705] Kernel panic - not syncing: panic_on_warn set ... [ 48.904705] [ 48.912080] CPU: 1 PID: 1789 Comm: syz-executor367 Tainted: G B 4.14.145+ #0 [ 48.920370] Call Trace: [ 48.922939] dump_stack+0xca/0x134 [ 48.926469] panic+0x1ea/0x3d3 [ 48.929637] ? add_taint.cold+0x16/0x16 [ 48.933590] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.937972] end_report+0x43/0x49 [ 48.941402] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.945859] __kasan_report.cold+0xd/0x41 [ 48.949991] ? kvm_guest_cpu_init+0x220/0x220 [ 48.954467] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.958856] tcp_init_tso_segs+0x19d/0x1f0 [ 48.963069] ? tcp_tso_segs+0x7b/0x1c0 [ 48.966936] tcp_write_xmit+0x15a/0x4730 [ 48.970990] ? ip6_mtu+0x206/0x330 [ 48.974511] ? lock_downgrade+0x5d0/0x5d0 [ 48.978635] ? lock_acquire+0x12b/0x360 [ 48.982592] __tcp_push_pending_frames+0xa0/0x230 [ 48.987412] tcp_send_fin+0x154/0xbc0 [ 48.991190] tcp_close+0xc62/0xf40 [ 48.994704] ? lock_acquire+0x12b/0x360 [ 48.998653] ? __sock_release+0x86/0x2c0 [ 49.002691] inet_release+0xe9/0x1c0 [ 49.006383] inet6_release+0x4c/0x70 [ 49.010084] __sock_release+0xd2/0x2c0 [ 49.013957] ? __sock_release+0x2c0/0x2c0 [ 49.018095] sock_close+0x15/0x20 [ 49.021535] __fput+0x25e/0x710 [ 49.024794] task_work_run+0x125/0x1a0 [ 49.028660] do_exit+0x9cb/0x2a20 [ 49.032101] ? futex_wake+0x15b/0x440 [ 49.035877] ? mm_update_next_owner+0x610/0x610 [ 49.040523] ? get_signal+0x334/0x1cc0 [ 49.044384] ? lock_downgrade+0x5d0/0x5d0 [ 49.048506] ? lock_acquire+0x12b/0x360 [ 49.052470] ? get_signal+0x1e7/0x1cc0 [ 49.056333] do_group_exit+0x100/0x2e0 [ 49.060197] get_signal+0x39f/0x1cc0 [ 49.063891] do_signal+0x96/0x15d0 [ 49.067406] ? inet_sendmsg+0x163/0x520 [ 49.071358] ? fput+0x19/0x150 [ 49.074525] ? setup_sigcontext+0x810/0x810 [ 49.078821] ? SyS_getpeername+0x250/0x250 [ 49.083040] ? SyS_futex+0x1c5/0x2c3 [ 49.086741] ? SyS_futex+0x1cf/0x2c3 [ 49.090430] ? do_futex+0x1980/0x1980 [ 49.094207] ? exit_to_usermode_loop+0xcd/0x160 [ 49.098851] exit_to_usermode_loop+0x11d/0x160 [ 49.103425] do_syscall_64+0x3a3/0x520 [ 49.107294] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.112462] RIP: 0033:0x445899 [ 49.115644] RSP: 002b:00007f39771e5da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 49.123334] RAX: 0000000000000001 RBX: 00000000006dac28 RCX: 0000000000445899 [ 49.130582] RDX: 000000000000001c RSI: 0000000000000081 RDI: 00000000006dac2c [ 49.137836] RBP: 00000000006dac20 R08: 000000000000001c R09: 0000000000000000 [ 49.145086] R10: 0000000020000280 R11: 0000000000000246 R12: 00000000006dac2c [ 49.152335] R13: 0000000000000000 R14: 0000000000000000 R15: 20c49ba5e353f7cf [ 49.160090] Kernel Offset: 0x18e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 49.170991] Rebooting in 86400 seconds..