[....] 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: [ 41.214463] random: sshd: uninitialized urandom read (32 bytes read) [ 41.577145] audit: type=1400 audit(1569028175.903:6): avc: denied { map } for pid=1775 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 [ 41.634064] random: sshd: uninitialized urandom read (32 bytes read) [ 42.169646] random: sshd: uninitialized urandom read (32 bytes read) [ 42.321373] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.1.28' (ECDSA) to the list of known hosts. [ 47.819660] random: sshd: uninitialized urandom read (32 bytes read) [ 47.911141] audit: type=1400 audit(1569028182.243:7): avc: denied { map } for pid=1793 comm="syz-executor624" path="/root/syz-executor624313577" dev="sda1" ino=16461 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 [ 48.690479] ================================================================== [ 48.698098] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 48.704842] Read of size 2 at addr ffff8881d2659930 by task syz-executor624/1794 [ 48.712352] [ 48.713986] CPU: 1 PID: 1794 Comm: syz-executor624 Not tainted 4.14.145+ #0 [ 48.721085] Call Trace: [ 48.723658] dump_stack+0xca/0x134 [ 48.727220] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.731621] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.736007] print_address_description+0x60/0x226 [ 48.740842] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.745244] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.749716] __kasan_report.cold+0x1a/0x41 [ 48.753937] ? kvm_guest_cpu_init+0x220/0x220 [ 48.758416] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.762807] tcp_init_tso_segs+0x19d/0x1f0 [ 48.767036] ? tcp_tso_segs+0x7b/0x1c0 [ 48.771002] tcp_write_xmit+0x15a/0x4730 [ 48.775047] ? memset+0x20/0x40 [ 48.778315] __tcp_push_pending_frames+0xa0/0x230 [ 48.783138] tcp_send_fin+0x154/0xbc0 [ 48.786923] tcp_close+0xc62/0xf40 [ 48.790447] inet_release+0xe9/0x1c0 [ 48.794153] __sock_release+0xd2/0x2c0 [ 48.798018] ? __sock_release+0x2c0/0x2c0 [ 48.802145] sock_close+0x15/0x20 [ 48.805583] __fput+0x25e/0x710 [ 48.808849] task_work_run+0x125/0x1a0 [ 48.812729] do_exit+0x9cb/0x2a20 [ 48.816181] ? mm_update_next_owner+0x610/0x610 [ 48.820838] do_group_exit+0x100/0x2e0 [ 48.824706] SyS_exit_group+0x19/0x20 [ 48.828482] ? do_group_exit+0x2e0/0x2e0 [ 48.832520] do_syscall_64+0x19b/0x520 [ 48.836391] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.841560] RIP: 0033:0x440618 [ 48.844734] RSP: 002b:00007ffe42518ed8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.852421] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 48.859669] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 48.866923] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.874171] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 48.881421] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 48.888683] [ 48.890287] Allocated by task 1794: [ 48.893912] __kasan_kmalloc.part.0+0x53/0xc0 [ 48.898383] kmem_cache_alloc+0xee/0x360 [ 48.902438] __alloc_skb+0xea/0x5c0 [ 48.906131] sk_stream_alloc_skb+0xf4/0x8a0 [ 48.910438] tcp_sendmsg_locked+0xf11/0x2f50 [ 48.914838] tcp_sendmsg+0x2b/0x40 [ 48.918355] inet_sendmsg+0x15b/0x520 [ 48.922135] sock_sendmsg+0xb7/0x100 [ 48.925839] SyS_sendto+0x1de/0x2f0 [ 48.929446] do_syscall_64+0x19b/0x520 [ 48.933318] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.938500] 0xffffffffffffffff [ 48.941758] [ 48.943361] Freed by task 1794: [ 48.946626] __kasan_slab_free+0x164/0x210 [ 48.950837] kmem_cache_free+0xd7/0x3b0 [ 48.954788] kfree_skbmem+0x84/0x110 [ 48.958484] tcp_remove_empty_skb+0x264/0x320 [ 48.962966] tcp_sendmsg_locked+0x1c09/0x2f50 [ 48.967451] tcp_sendmsg+0x2b/0x40 [ 48.970981] inet_sendmsg+0x15b/0x520 [ 48.974758] sock_sendmsg+0xb7/0x100 [ 48.979928] SyS_sendto+0x1de/0x2f0 [ 48.983548] do_syscall_64+0x19b/0x520 [ 48.987424] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.992601] 0xffffffffffffffff [ 48.995862] [ 48.997481] The buggy address belongs to the object at ffff8881d2659900 [ 48.997481] which belongs to the cache skbuff_fclone_cache of size 456 [ 49.010812] The buggy address is located 48 bytes inside of [ 49.010812] 456-byte region [ffff8881d2659900, ffff8881d2659ac8) [ 49.022576] The buggy address belongs to the page: [ 49.027491] page:ffffea0007499600 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 49.037447] flags: 0x4000000000010200(slab|head) [ 49.042182] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 49.050039] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 49.057891] page dumped because: kasan: bad access detected [ 49.063579] [ 49.065182] Memory state around the buggy address: [ 49.070085] ffff8881d2659800: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 49.077449] ffff8881d2659880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 49.084796] >ffff8881d2659900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.092134] ^ [ 49.097309] ffff8881d2659980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.104661] ffff8881d2659a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 49.111999] ================================================================== [ 49.119356] Disabling lock debugging due to kernel taint [ 49.126782] Kernel panic - not syncing: panic_on_warn set ... [ 49.126782] [ 49.134148] CPU: 1 PID: 1794 Comm: syz-executor624 Tainted: G B 4.14.145+ #0 [ 49.142535] Call Trace: [ 49.145106] dump_stack+0xca/0x134 [ 49.148627] panic+0x1ea/0x3d3 [ 49.151800] ? add_taint.cold+0x16/0x16 [ 49.155751] ? tcp_init_tso_segs+0x19d/0x1f0 [ 49.160140] ? ___preempt_schedule+0x16/0x18 [ 49.164526] ? tcp_init_tso_segs+0x19d/0x1f0 [ 49.168933] end_report+0x43/0x49 [ 49.172363] ? tcp_init_tso_segs+0x19d/0x1f0 [ 49.176746] __kasan_report.cold+0xd/0x41 [ 49.180902] ? kvm_guest_cpu_init+0x220/0x220 [ 49.185373] ? tcp_init_tso_segs+0x19d/0x1f0 [ 49.189757] tcp_init_tso_segs+0x19d/0x1f0 [ 49.193968] ? tcp_tso_segs+0x7b/0x1c0 [ 49.197829] tcp_write_xmit+0x15a/0x4730 [ 49.201871] ? memset+0x20/0x40 [ 49.205139] __tcp_push_pending_frames+0xa0/0x230 [ 49.209966] tcp_send_fin+0x154/0xbc0 [ 49.213754] tcp_close+0xc62/0xf40 [ 49.217278] inet_release+0xe9/0x1c0 [ 49.220970] __sock_release+0xd2/0x2c0 [ 49.224834] ? __sock_release+0x2c0/0x2c0 [ 49.228956] sock_close+0x15/0x20 [ 49.232396] __fput+0x25e/0x710 [ 49.235656] task_work_run+0x125/0x1a0 [ 49.239522] do_exit+0x9cb/0x2a20 [ 49.242955] ? mm_update_next_owner+0x610/0x610 [ 49.247604] do_group_exit+0x100/0x2e0 [ 49.251467] SyS_exit_group+0x19/0x20 [ 49.255242] ? do_group_exit+0x2e0/0x2e0 [ 49.259277] do_syscall_64+0x19b/0x520 [ 49.263147] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 49.268314] RIP: 0033:0x440618 [ 49.271486] RSP: 002b:00007ffe42518ed8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 49.279517] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440618 [ 49.286774] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 49.294037] RBP: 00000000004c6970 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 49.301284] R10: 0000000020000802 R11: 0000000000000246 R12: 0000000000000001 [ 49.308703] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 49.316727] Kernel Offset: 0x22400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 49.327836] Rebooting in 86400 seconds..