[....] 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: [ 33.315624] random: sshd: uninitialized urandom read (32 bytes read) [ 33.887811] audit: type=1400 audit(1569067225.120:6): avc: denied { map } for pid=1771 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 [ 33.926061] random: sshd: uninitialized urandom read (32 bytes read) [ 34.457919] random: sshd: uninitialized urandom read (32 bytes read) [ 34.614131] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.103' (ECDSA) to the list of known hosts. [ 40.012933] random: sshd: uninitialized urandom read (32 bytes read) [ 40.102658] audit: type=1400 audit(1569067231.340:7): avc: denied { map } for pid=1783 comm="syz-executor055" path="/root/syz-executor055535621" 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 [ 40.950907] ================================================================== [ 40.958579] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 40.965322] Read of size 2 at addr ffff8881c431a030 by task syz-executor055/1784 [ 40.972833] [ 40.974445] CPU: 1 PID: 1784 Comm: syz-executor055 Not tainted 4.14.145+ #0 [ 40.981527] Call Trace: [ 40.984103] dump_stack+0xca/0x134 [ 40.987652] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.992040] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.996429] print_address_description+0x60/0x226 [ 41.001250] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.005642] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.010030] __kasan_report.cold+0x1a/0x41 [ 41.014248] ? kvm_guest_cpu_init+0x220/0x220 [ 41.018734] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.023126] tcp_init_tso_segs+0x19d/0x1f0 [ 41.027349] ? tcp_tso_segs+0x7b/0x1c0 [ 41.031224] tcp_write_xmit+0x15a/0x4730 [ 41.035268] ? memset+0x20/0x40 [ 41.038532] __tcp_push_pending_frames+0xa0/0x230 [ 41.043362] tcp_send_fin+0x154/0xbc0 [ 41.047157] tcp_close+0xc62/0xf40 [ 41.050682] inet_release+0xe9/0x1c0 [ 41.054548] __sock_release+0xd2/0x2c0 [ 41.058580] ? __sock_release+0x2c0/0x2c0 [ 41.062883] sock_close+0x15/0x20 [ 41.066351] __fput+0x25e/0x710 [ 41.069712] task_work_run+0x125/0x1a0 [ 41.073960] do_exit+0x9cb/0x2a20 [ 41.077409] ? mm_update_next_owner+0x610/0x610 [ 41.082083] do_group_exit+0x100/0x2e0 [ 41.085953] SyS_exit_group+0x19/0x20 [ 41.089832] ? do_group_exit+0x2e0/0x2e0 [ 41.094036] do_syscall_64+0x19b/0x520 [ 41.097909] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.103091] RIP: 0033:0x440b48 [ 41.106271] RSP: 002b:00007ffe1e163d08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.113968] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 41.121218] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 41.128476] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.135729] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 41.142995] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 41.150271] [ 41.151885] Allocated by task 1784: [ 41.155507] __kasan_kmalloc.part.0+0x53/0xc0 [ 41.159998] kmem_cache_alloc+0xee/0x360 [ 41.164047] __alloc_skb+0xea/0x5c0 [ 41.167744] sk_stream_alloc_skb+0xf4/0x8a0 [ 41.172045] tcp_sendmsg_locked+0xf11/0x2f50 [ 41.176429] tcp_sendmsg+0x2b/0x40 [ 41.180212] inet_sendmsg+0x15b/0x520 [ 41.184001] sock_sendmsg+0xb7/0x100 [ 41.188038] SyS_sendto+0x1de/0x2f0 [ 41.191643] do_syscall_64+0x19b/0x520 [ 41.195507] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.200672] 0xffffffffffffffff [ 41.203925] [ 41.205530] Freed by task 1784: [ 41.208876] __kasan_slab_free+0x164/0x210 [ 41.213086] kmem_cache_free+0xd7/0x3b0 [ 41.217044] kfree_skbmem+0x84/0x110 [ 41.220746] tcp_remove_empty_skb+0x264/0x320 [ 41.225231] tcp_sendmsg_locked+0x1c09/0x2f50 [ 41.229719] tcp_sendmsg+0x2b/0x40 [ 41.233238] inet_sendmsg+0x15b/0x520 [ 41.237068] sock_sendmsg+0xb7/0x100 [ 41.240794] SyS_sendto+0x1de/0x2f0 [ 41.244410] do_syscall_64+0x19b/0x520 [ 41.248296] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.253620] 0xffffffffffffffff [ 41.256894] [ 41.258501] The buggy address belongs to the object at ffff8881c431a000 [ 41.258501] which belongs to the cache skbuff_fclone_cache of size 456 [ 41.271830] The buggy address is located 48 bytes inside of [ 41.271830] 456-byte region [ffff8881c431a000, ffff8881c431a1c8) [ 41.284394] The buggy address belongs to the page: [ 41.289314] page:ffffea000710c680 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 41.299267] flags: 0x4000000000010200(slab|head) [ 41.304006] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 41.311875] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 41.319748] page dumped because: kasan: bad access detected [ 41.325443] [ 41.327054] Memory state around the buggy address: [ 41.331965] ffff8881c4319f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 41.339329] ffff8881c4319f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 41.346672] >ffff8881c431a000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.354321] ^ [ 41.359336] ffff8881c431a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.367021] ffff8881c431a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 41.374581] ================================================================== [ 41.382025] Disabling lock debugging due to kernel taint [ 41.387629] Kernel panic - not syncing: panic_on_warn set ... [ 41.387629] [ 41.395272] CPU: 1 PID: 1784 Comm: syz-executor055 Tainted: G B 4.14.145+ #0 [ 41.403768] Call Trace: [ 41.406460] dump_stack+0xca/0x134 [ 41.409984] panic+0x1ea/0x3d3 [ 41.413172] ? add_taint.cold+0x16/0x16 [ 41.417200] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.421630] ? ___preempt_schedule+0x16/0x18 [ 41.426026] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.430440] end_report+0x43/0x49 [ 41.433895] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.438305] __kasan_report.cold+0xd/0x41 [ 41.442450] ? kvm_guest_cpu_init+0x220/0x220 [ 41.447018] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.451416] tcp_init_tso_segs+0x19d/0x1f0 [ 41.455631] ? tcp_tso_segs+0x7b/0x1c0 [ 41.459630] tcp_write_xmit+0x15a/0x4730 [ 41.463687] ? memset+0x20/0x40 [ 41.466958] __tcp_push_pending_frames+0xa0/0x230 [ 41.471788] tcp_send_fin+0x154/0xbc0 [ 41.475571] tcp_close+0xc62/0xf40 [ 41.479103] inet_release+0xe9/0x1c0 [ 41.482937] __sock_release+0xd2/0x2c0 [ 41.486817] ? __sock_release+0x2c0/0x2c0 [ 41.490951] sock_close+0x15/0x20 [ 41.494411] __fput+0x25e/0x710 [ 41.497703] task_work_run+0x125/0x1a0 [ 41.501574] do_exit+0x9cb/0x2a20 [ 41.505010] ? mm_update_next_owner+0x610/0x610 [ 41.509664] do_group_exit+0x100/0x2e0 [ 41.513529] SyS_exit_group+0x19/0x20 [ 41.517306] ? do_group_exit+0x2e0/0x2e0 [ 41.521354] do_syscall_64+0x19b/0x520 [ 41.525234] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.530440] RIP: 0033:0x440b48 [ 41.533613] RSP: 002b:00007ffe1e163d08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.541326] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440b48 [ 41.548751] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 41.556006] RBP: 00000000004c6fd0 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.563262] R10: 0000000020000800 R11: 0000000000000246 R12: 0000000000000001 [ 41.570527] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 41.578424] Kernel Offset: 0x29000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 41.589330] Rebooting in 86400 seconds..