[....] 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: [ 29.349847] random: sshd: uninitialized urandom read (32 bytes read) [ 29.958280] audit: type=1400 audit(1569063910.228:6): avc: denied { map } for pid=1772 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 [ 30.008446] random: sshd: uninitialized urandom read (32 bytes read) [ 30.537693] random: sshd: uninitialized urandom read (32 bytes read) [ 30.724945] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.22' (ECDSA) to the list of known hosts. [ 36.240703] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 36.335204] audit: type=1400 audit(1569063916.608:7): avc: denied { map } for pid=1790 comm="syz-executor247" path="/root/syz-executor247358015" 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 [ 36.345208] ================================================================== [ 36.370595] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 36.377601] Read of size 2 at addr ffff8881d0ffd430 by task syz-executor247/1790 [ 36.385121] [ 36.386742] CPU: 0 PID: 1790 Comm: syz-executor247 Not tainted 4.14.145+ #0 [ 36.394085] Call Trace: [ 36.396660] dump_stack+0xca/0x134 [ 36.400476] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.405157] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.409728] print_address_description+0x60/0x226 [ 36.414747] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.419156] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.423565] __kasan_report.cold+0x1a/0x41 [ 36.427937] ? kvm_guest_cpu_init+0x220/0x220 [ 36.432483] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.436932] tcp_init_tso_segs+0x19d/0x1f0 [ 36.441166] ? tcp_tso_segs+0x7b/0x1c0 [ 36.445195] tcp_write_xmit+0x15a/0x4730 [ 36.449326] ? ip6_mtu+0x206/0x330 [ 36.453865] ? lock_downgrade+0x5d0/0x5d0 [ 36.457997] ? lock_acquire+0x12b/0x360 [ 36.461969] __tcp_push_pending_frames+0xa0/0x230 [ 36.466797] tcp_send_fin+0x154/0xbc0 [ 36.470590] tcp_close+0xc62/0xf40 [ 36.474113] ? lock_acquire+0x12b/0x360 [ 36.478153] ? __sock_release+0x86/0x2c0 [ 36.482893] inet_release+0xe9/0x1c0 [ 36.486715] inet6_release+0x4c/0x70 [ 36.490532] __sock_release+0xd2/0x2c0 [ 36.494945] ? __sock_release+0x2c0/0x2c0 [ 36.499196] sock_close+0x15/0x20 [ 36.502652] __fput+0x25e/0x710 [ 36.506189] task_work_run+0x125/0x1a0 [ 36.510073] do_exit+0x9cb/0x2a20 [ 36.513689] ? mm_update_next_owner+0x610/0x610 [ 36.518366] ? SyS_socket+0x143/0x1e0 [ 36.522172] do_group_exit+0x100/0x2e0 [ 36.526164] SyS_exit_group+0x19/0x20 [ 36.529953] ? do_group_exit+0x2e0/0x2e0 [ 36.534003] do_syscall_64+0x19b/0x520 [ 36.537879] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 36.543055] RIP: 0033:0x43ee88 [ 36.546221] RSP: 002b:00007ffd791c7ef8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 36.556281] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 36.563547] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 36.570906] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 36.578285] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 36.585554] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 36.592837] [ 36.594448] Allocated by task 1790: [ 36.598063] __kasan_kmalloc.part.0+0x53/0xc0 [ 36.602537] kmem_cache_alloc+0xee/0x360 [ 36.606587] __alloc_skb+0xea/0x5c0 [ 36.610192] sk_stream_alloc_skb+0xf4/0x8a0 [ 36.615699] tcp_sendmsg_locked+0xf11/0x2f50 [ 36.620098] tcp_sendmsg+0x2b/0x40 [ 36.623719] inet_sendmsg+0x15b/0x520 [ 36.627570] sock_sendmsg+0xb7/0x100 [ 36.631265] SyS_sendto+0x1de/0x2f0 [ 36.635023] do_syscall_64+0x19b/0x520 [ 36.638898] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 36.644072] 0xffffffffffffffff [ 36.647482] [ 36.649094] Freed by task 1790: [ 36.652367] __kasan_slab_free+0x164/0x210 [ 36.656593] kmem_cache_free+0xd7/0x3b0 [ 36.660556] kfree_skbmem+0x84/0x110 [ 36.664429] tcp_remove_empty_skb+0x264/0x320 [ 36.668925] tcp_sendmsg_locked+0x1c09/0x2f50 [ 36.673496] tcp_sendmsg+0x2b/0x40 [ 36.677026] inet_sendmsg+0x15b/0x520 [ 36.680907] sock_sendmsg+0xb7/0x100 [ 36.684596] SyS_sendto+0x1de/0x2f0 [ 36.688210] do_syscall_64+0x19b/0x520 [ 36.692250] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 36.697414] 0xffffffffffffffff [ 36.700666] [ 36.702297] The buggy address belongs to the object at ffff8881d0ffd400 [ 36.702297] which belongs to the cache skbuff_fclone_cache of size 456 [ 36.715699] The buggy address is located 48 bytes inside of [ 36.715699] 456-byte region [ffff8881d0ffd400, ffff8881d0ffd5c8) [ 36.730350] The buggy address belongs to the page: [ 36.735336] page:ffffea000743ff00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 36.745394] flags: 0x4000000000010200(slab|head) [ 36.750305] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 36.758309] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 36.766318] page dumped because: kasan: bad access detected [ 36.772436] [ 36.774055] Memory state around the buggy address: [ 36.778962] ffff8881d0ffd300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 36.786305] ffff8881d0ffd380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 36.793646] >ffff8881d0ffd400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.800990] ^ [ 36.805999] ffff8881d0ffd480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.813539] ffff8881d0ffd500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 36.821255] ================================================================== [ 36.828594] Disabling lock debugging due to kernel taint [ 36.835151] Kernel panic - not syncing: panic_on_warn set ... [ 36.835151] [ 36.842563] CPU: 0 PID: 1790 Comm: syz-executor247 Tainted: G B 4.14.145+ #0 [ 36.850859] Call Trace: [ 36.853798] dump_stack+0xca/0x134 [ 36.857437] panic+0x1ea/0x3d3 [ 36.860615] ? add_taint.cold+0x16/0x16 [ 36.864590] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.868990] ? ___preempt_schedule+0x16/0x18 [ 36.873383] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.877870] end_report+0x43/0x49 [ 36.881392] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.885778] __kasan_report.cold+0xd/0x41 [ 36.889906] ? kvm_guest_cpu_init+0x220/0x220 [ 36.894390] ? tcp_init_tso_segs+0x19d/0x1f0 [ 36.898788] tcp_init_tso_segs+0x19d/0x1f0 [ 36.903006] ? tcp_tso_segs+0x7b/0x1c0 [ 36.906884] tcp_write_xmit+0x15a/0x4730 [ 36.910927] ? ip6_mtu+0x206/0x330 [ 36.914446] ? lock_downgrade+0x5d0/0x5d0 [ 36.918570] ? lock_acquire+0x12b/0x360 [ 36.922524] __tcp_push_pending_frames+0xa0/0x230 [ 36.927354] tcp_send_fin+0x154/0xbc0 [ 36.931136] tcp_close+0xc62/0xf40 [ 36.935609] ? lock_acquire+0x12b/0x360 [ 36.939704] ? __sock_release+0x86/0x2c0 [ 36.943829] inet_release+0xe9/0x1c0 [ 36.947532] inet6_release+0x4c/0x70 [ 36.951254] __sock_release+0xd2/0x2c0 [ 36.955225] ? __sock_release+0x2c0/0x2c0 [ 36.959362] sock_close+0x15/0x20 [ 36.962922] __fput+0x25e/0x710 [ 36.966189] task_work_run+0x125/0x1a0 [ 36.970069] do_exit+0x9cb/0x2a20 [ 36.973610] ? mm_update_next_owner+0x610/0x610 [ 36.978262] ? SyS_socket+0x143/0x1e0 [ 36.982217] do_group_exit+0x100/0x2e0 [ 36.986083] SyS_exit_group+0x19/0x20 [ 36.989861] ? do_group_exit+0x2e0/0x2e0 [ 36.993901] do_syscall_64+0x19b/0x520 [ 36.997793] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 37.002985] RIP: 0033:0x43ee88 [ 37.006164] RSP: 002b:00007ffd791c7ef8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 37.013853] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 37.021121] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 37.028371] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 37.035638] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 37.042887] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 37.050943] Kernel Offset: 0xc200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 37.061779] Rebooting in 86400 seconds..