[....] 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: [ 25.287195] random: sshd: uninitialized urandom read (32 bytes read) [ 25.677447] audit: type=1400 audit(1569048143.861:6): avc: denied { map } for pid=1769 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 [ 25.722057] random: sshd: uninitialized urandom read (32 bytes read) [ 26.247884] random: sshd: uninitialized urandom read (32 bytes read) [ 26.402169] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.202' (ECDSA) to the list of known hosts. [ 31.899389] random: sshd: uninitialized urandom read (32 bytes read) [ 31.993245] audit: type=1400 audit(1569048150.181:7): avc: denied { map } for pid=1781 comm="syz-executor644" path="/root/syz-executor644954074" 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 executing program [ 32.731144] ================================================================== [ 32.739431] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 32.746185] Read of size 2 at addr ffff8881c4011430 by task syz-executor644/1782 [ 32.754308] [ 32.755922] CPU: 0 PID: 1782 Comm: syz-executor644 Not tainted 4.14.145+ #0 [ 32.763173] Call Trace: [ 32.765762] dump_stack+0xca/0x134 [ 32.769368] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.773765] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.778261] print_address_description+0x60/0x226 [ 32.783098] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.787495] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.791886] __kasan_report.cold+0x1a/0x41 [ 32.796114] ? kvm_guest_cpu_init+0x220/0x220 [ 32.800601] ? tcp_init_tso_segs+0x19d/0x1f0 [ 32.804992] tcp_init_tso_segs+0x19d/0x1f0 [ 32.809304] ? tcp_tso_segs+0x7b/0x1c0 [ 32.813194] tcp_write_xmit+0x15a/0x4730 [ 32.817243] ? memset+0x20/0x40 [ 32.820691] __tcp_push_pending_frames+0xa0/0x230 [ 32.825561] tcp_send_fin+0x154/0xbc0 [ 32.829356] tcp_close+0xc62/0xf40 [ 32.832901] inet_release+0xe9/0x1c0 [ 32.836601] __sock_release+0xd2/0x2c0 [ 32.840832] ? __sock_release+0x2c0/0x2c0 [ 32.844969] sock_close+0x15/0x20 [ 32.848444] __fput+0x25e/0x710 [ 32.851716] task_work_run+0x125/0x1a0 [ 32.855695] do_exit+0x9cb/0x2a20 [ 32.859220] ? mm_update_next_owner+0x610/0x610 [ 32.863894] do_group_exit+0x100/0x2e0 [ 32.867791] SyS_exit_group+0x19/0x20 [ 32.871592] ? do_group_exit+0x2e0/0x2e0 [ 32.875642] do_syscall_64+0x19b/0x520 [ 32.879520] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.884796] RIP: 0033:0x440618 [ 32.887968] RSP: 002b:00007fff5fe30098 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 32.895675] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 32.902926] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 32.910263] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 32.917612] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 32.925077] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 32.932561] [ 32.934174] Allocated by task 1782: [ 32.937872] __kasan_kmalloc.part.0+0x53/0xc0 [ 32.942437] kmem_cache_alloc+0xee/0x360 [ 32.946829] __alloc_skb+0xea/0x5c0 [ 32.950559] sk_stream_alloc_skb+0xf4/0x8a0 [ 32.954882] tcp_sendmsg_locked+0xf11/0x2f50 [ 32.959271] tcp_sendmsg+0x2b/0x40 [ 32.962880] inet_sendmsg+0x15b/0x520 [ 32.966665] sock_sendmsg+0xb7/0x100 [ 32.970357] SyS_sendto+0x1de/0x2f0 [ 32.973964] do_syscall_64+0x19b/0x520 [ 32.977924] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 32.983269] 0xffffffffffffffff [ 32.986707] [ 32.988318] Freed by task 1782: [ 32.991608] __kasan_slab_free+0x164/0x210 [ 32.995836] kmem_cache_free+0xd7/0x3b0 [ 32.999789] kfree_skbmem+0x84/0x110 [ 33.003672] tcp_remove_empty_skb+0x264/0x320 [ 33.008149] tcp_sendmsg_locked+0x1c09/0x2f50 [ 33.012630] tcp_sendmsg+0x2b/0x40 [ 33.016158] inet_sendmsg+0x15b/0x520 [ 33.019949] sock_sendmsg+0xb7/0x100 [ 33.023643] SyS_sendto+0x1de/0x2f0 [ 33.027250] do_syscall_64+0x19b/0x520 [ 33.031296] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 33.036650] 0xffffffffffffffff [ 33.040095] [ 33.041722] The buggy address belongs to the object at ffff8881c4011400 [ 33.041722] which belongs to the cache skbuff_fclone_cache of size 456 [ 33.055170] The buggy address is located 48 bytes inside of [ 33.055170] 456-byte region [ffff8881c4011400, ffff8881c40115c8) [ 33.066940] The buggy address belongs to the page: [ 33.071923] page:ffffea0007100400 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 33.082375] flags: 0x4000000000010200(slab|head) [ 33.087200] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 33.095064] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 33.103020] page dumped because: kasan: bad access detected [ 33.108813] [ 33.110419] Memory state around the buggy address: [ 33.115440] ffff8881c4011300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 33.122782] ffff8881c4011380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 33.130126] >ffff8881c4011400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.137653] ^ [ 33.142588] ffff8881c4011480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.149959] ffff8881c4011500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 33.157453] ================================================================== [ 33.164812] Disabling lock debugging due to kernel taint [ 33.171076] Kernel panic - not syncing: panic_on_warn set ... [ 33.171076] [ 33.178634] CPU: 0 PID: 1782 Comm: syz-executor644 Tainted: G B 4.14.145+ #0 [ 33.187053] Call Trace: [ 33.189641] dump_stack+0xca/0x134 [ 33.193173] panic+0x1ea/0x3d3 [ 33.196348] ? add_taint.cold+0x16/0x16 [ 33.200408] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.205116] ? ___preempt_schedule+0x16/0x18 [ 33.210850] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.215471] end_report+0x43/0x49 [ 33.219019] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.224292] __kasan_report.cold+0xd/0x41 [ 33.228744] ? kvm_guest_cpu_init+0x220/0x220 [ 33.233233] ? tcp_init_tso_segs+0x19d/0x1f0 [ 33.237645] tcp_init_tso_segs+0x19d/0x1f0 [ 33.241881] ? tcp_tso_segs+0x7b/0x1c0 [ 33.245750] tcp_write_xmit+0x15a/0x4730 [ 33.249884] ? memset+0x20/0x40 [ 33.253335] __tcp_push_pending_frames+0xa0/0x230 [ 33.258166] tcp_send_fin+0x154/0xbc0 [ 33.261973] tcp_close+0xc62/0xf40 [ 33.265501] inet_release+0xe9/0x1c0 [ 33.269214] __sock_release+0xd2/0x2c0 [ 33.273089] ? __sock_release+0x2c0/0x2c0 [ 33.277228] sock_close+0x15/0x20 [ 33.280677] __fput+0x25e/0x710 [ 33.284049] task_work_run+0x125/0x1a0 [ 33.288015] do_exit+0x9cb/0x2a20 [ 33.291475] ? mm_update_next_owner+0x610/0x610 [ 33.296304] do_group_exit+0x100/0x2e0 [ 33.300173] SyS_exit_group+0x19/0x20 [ 33.304043] ? do_group_exit+0x2e0/0x2e0 [ 33.308176] do_syscall_64+0x19b/0x520 [ 33.312204] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 33.317386] RIP: 0033:0x440618 [ 33.320558] RSP: 002b:00007fff5fe30098 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 33.328249] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 33.335504] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 33.342874] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 33.350210] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 33.357552] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 33.366127] Kernel Offset: 0x14e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 33.377159] Rebooting in 86400 seconds..