[....] 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: [ 40.775192] random: sshd: uninitialized urandom read (32 bytes read) [ 41.232133] audit: type=1400 audit(1569046771.640:6): avc: denied { map } for pid=1773 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 [ 41.274389] random: sshd: uninitialized urandom read (32 bytes read) [ 41.775178] random: sshd: uninitialized urandom read (32 bytes read) [ 41.931593] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.85' (ECDSA) to the list of known hosts. [ 47.337065] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 47.431430] audit: type=1400 audit(1569046777.840:7): avc: denied { map } for pid=1787 comm="syz-executor730" path="/root/syz-executor730177314" 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 [ 47.461600] ================================================================== [ 47.469094] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 47.475827] Read of size 2 at addr ffff8881d270f430 by task syz-executor730/1787 [ 47.483364] [ 47.484974] CPU: 0 PID: 1787 Comm: syz-executor730 Not tainted 4.14.145+ #0 [ 47.492047] Call Trace: [ 47.494633] dump_stack+0xca/0x134 [ 47.498164] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.502550] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.506938] print_address_description+0x60/0x226 [ 47.511772] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.516156] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.520544] __kasan_report.cold+0x1a/0x41 [ 47.524771] ? kvm_guest_cpu_init+0x220/0x220 [ 47.529254] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.533643] tcp_init_tso_segs+0x19d/0x1f0 [ 47.537852] ? tcp_tso_segs+0x7b/0x1c0 [ 47.541722] tcp_write_xmit+0x15a/0x4730 [ 47.545764] ? ip6_mtu+0x206/0x330 [ 47.549282] ? lock_downgrade+0x5d0/0x5d0 [ 47.553417] ? lock_acquire+0x12b/0x360 [ 47.557385] __tcp_push_pending_frames+0xa0/0x230 [ 47.562219] tcp_send_fin+0x154/0xbc0 [ 47.566002] tcp_close+0xc62/0xf40 [ 47.569536] ? lock_acquire+0x12b/0x360 [ 47.573488] ? __sock_release+0x86/0x2c0 [ 47.577531] inet_release+0xe9/0x1c0 [ 47.581226] inet6_release+0x4c/0x70 [ 47.584921] __sock_release+0xd2/0x2c0 [ 47.588788] ? __sock_release+0x2c0/0x2c0 [ 47.592912] sock_close+0x15/0x20 [ 47.596343] __fput+0x25e/0x710 [ 47.599608] task_work_run+0x125/0x1a0 [ 47.603479] do_exit+0x9cb/0x2a20 [ 47.606917] ? mm_update_next_owner+0x610/0x610 [ 47.611572] ? SyS_socket+0x143/0x1e0 [ 47.615363] do_group_exit+0x100/0x2e0 [ 47.619231] SyS_exit_group+0x19/0x20 [ 47.623008] ? do_group_exit+0x2e0/0x2e0 [ 47.627047] do_syscall_64+0x19b/0x520 [ 47.630930] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.636099] RIP: 0033:0x43ee88 [ 47.639277] RSP: 002b:00007ffd4bc99a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 47.646975] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 47.654225] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 47.661472] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 47.668718] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 47.675966] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 47.683238] [ 47.684845] Allocated by task 1787: [ 47.688451] __kasan_kmalloc.part.0+0x53/0xc0 [ 47.692925] kmem_cache_alloc+0xee/0x360 [ 47.696964] __alloc_skb+0xea/0x5c0 [ 47.700588] sk_stream_alloc_skb+0xf4/0x8a0 [ 47.704891] tcp_sendmsg_locked+0xf11/0x2f50 [ 47.709286] tcp_sendmsg+0x2b/0x40 [ 47.712815] inet_sendmsg+0x15b/0x520 [ 47.716594] sock_sendmsg+0xb7/0x100 [ 47.720284] SyS_sendto+0x1de/0x2f0 [ 47.723887] do_syscall_64+0x19b/0x520 [ 47.727768] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.732932] 0xffffffffffffffff [ 47.736184] [ 47.737791] Freed by task 1787: [ 47.741048] __kasan_slab_free+0x164/0x210 [ 47.745271] kmem_cache_free+0xd7/0x3b0 [ 47.749231] kfree_skbmem+0x84/0x110 [ 47.752921] tcp_remove_empty_skb+0x264/0x320 [ 47.757393] tcp_sendmsg_locked+0x1c09/0x2f50 [ 47.761869] tcp_sendmsg+0x2b/0x40 [ 47.765387] inet_sendmsg+0x15b/0x520 [ 47.769199] sock_sendmsg+0xb7/0x100 [ 47.772888] SyS_sendto+0x1de/0x2f0 [ 47.776491] do_syscall_64+0x19b/0x520 [ 47.780359] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 47.785520] 0xffffffffffffffff [ 47.788771] [ 47.790378] The buggy address belongs to the object at ffff8881d270f400 [ 47.790378] which belongs to the cache skbuff_fclone_cache of size 456 [ 47.803719] The buggy address is located 48 bytes inside of [ 47.803719] 456-byte region [ffff8881d270f400, ffff8881d270f5c8) [ 47.815486] The buggy address belongs to the page: [ 47.820406] page:ffffea000749c380 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 47.830369] flags: 0x4000000000010200(slab|head) [ 47.835116] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 47.842984] raw: dead000000000100 dead000000000200 ffff8881d6770400 0000000000000000 [ 47.850856] page dumped because: kasan: bad access detected [ 47.856551] [ 47.858166] Memory state around the buggy address: [ 47.863074] ffff8881d270f300: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 47.870412] ffff8881d270f380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 47.877772] >ffff8881d270f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.885123] ^ [ 47.890039] ffff8881d270f480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.897382] ffff8881d270f500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 47.904721] ================================================================== [ 47.912069] Disabling lock debugging due to kernel taint [ 47.918017] Kernel panic - not syncing: panic_on_warn set ... [ 47.918017] [ 47.925404] CPU: 0 PID: 1787 Comm: syz-executor730 Tainted: G B 4.14.145+ #0 [ 47.933708] Call Trace: [ 47.936281] dump_stack+0xca/0x134 [ 47.939798] panic+0x1ea/0x3d3 [ 47.942981] ? add_taint.cold+0x16/0x16 [ 47.946935] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.951335] ? ___preempt_schedule+0x16/0x18 [ 47.955719] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.960130] end_report+0x43/0x49 [ 47.963571] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.967968] __kasan_report.cold+0xd/0x41 [ 47.972111] ? kvm_guest_cpu_init+0x220/0x220 [ 47.976582] ? tcp_init_tso_segs+0x19d/0x1f0 [ 47.980968] tcp_init_tso_segs+0x19d/0x1f0 [ 47.985183] ? tcp_tso_segs+0x7b/0x1c0 [ 47.989061] tcp_write_xmit+0x15a/0x4730 [ 47.993114] ? ip6_mtu+0x206/0x330 [ 47.996641] ? lock_downgrade+0x5d0/0x5d0 [ 48.000764] ? lock_acquire+0x12b/0x360 [ 48.004817] __tcp_push_pending_frames+0xa0/0x230 [ 48.009670] tcp_send_fin+0x154/0xbc0 [ 48.013473] tcp_close+0xc62/0xf40 [ 48.017047] ? lock_acquire+0x12b/0x360 [ 48.020998] ? __sock_release+0x86/0x2c0 [ 48.025038] inet_release+0xe9/0x1c0 [ 48.028729] inet6_release+0x4c/0x70 [ 48.032419] __sock_release+0xd2/0x2c0 [ 48.036283] ? __sock_release+0x2c0/0x2c0 [ 48.040411] sock_close+0x15/0x20 [ 48.043852] __fput+0x25e/0x710 [ 48.047120] task_work_run+0x125/0x1a0 [ 48.050987] do_exit+0x9cb/0x2a20 [ 48.054486] ? mm_update_next_owner+0x610/0x610 [ 48.059204] ? SyS_socket+0x143/0x1e0 [ 48.062992] do_group_exit+0x100/0x2e0 [ 48.066860] SyS_exit_group+0x19/0x20 [ 48.070639] ? do_group_exit+0x2e0/0x2e0 [ 48.074678] do_syscall_64+0x19b/0x520 [ 48.078549] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.083716] RIP: 0033:0x43ee88 [ 48.086887] RSP: 002b:00007ffd4bc99a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.094571] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88 [ 48.101940] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 48.109198] RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.116450] R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000001 [ 48.123697] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 48.131012] Kernel Offset: 0x23400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 48.141921] Rebooting in 86400 seconds..