[....] 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: [ 40.448700] random: sshd: uninitialized urandom read (32 bytes read) [ 40.867118] audit: type=1400 audit(1569052297.975:6): 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 [ 40.906367] random: sshd: uninitialized urandom read (32 bytes read) [ 41.449538] random: sshd: uninitialized urandom read (32 bytes read) [ 41.607540] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.57' (ECDSA) to the list of known hosts. [ 47.089016] random: sshd: uninitialized urandom read (32 bytes read) [ 47.195588] audit: type=1400 audit(1569052304.305:7): avc: denied { map } for pid=1790 comm="syz-executor341" path="/root/syz-executor341425666" dev="sda1" ino=16482 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 [ 48.040635] ================================================================== [ 48.048337] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 48.055403] Read of size 2 at addr ffff8881d0461930 by task syz-executor341/1791 [ 48.062941] [ 48.065087] CPU: 0 PID: 1791 Comm: syz-executor341 Not tainted 4.14.145+ #0 [ 48.072266] Call Trace: [ 48.074864] dump_stack+0xca/0x134 [ 48.078390] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.082794] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.087207] print_address_description+0x60/0x226 [ 48.092048] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.096468] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.100900] __kasan_report.cold+0x1a/0x41 [ 48.105220] ? kvm_guest_cpu_init+0x220/0x220 [ 48.109807] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.114405] tcp_init_tso_segs+0x19d/0x1f0 [ 48.118756] ? tcp_tso_segs+0x7b/0x1c0 [ 48.122651] tcp_write_xmit+0x15a/0x4730 [ 48.126720] ? memset+0x20/0x40 [ 48.130085] __tcp_push_pending_frames+0xa0/0x230 [ 48.134946] tcp_send_fin+0x154/0xbc0 [ 48.138921] tcp_close+0xc62/0xf40 [ 48.142455] inet_release+0xe9/0x1c0 [ 48.146187] __sock_release+0xd2/0x2c0 [ 48.150241] ? __sock_release+0x2c0/0x2c0 [ 48.154713] sock_close+0x15/0x20 [ 48.158150] __fput+0x25e/0x710 [ 48.161506] task_work_run+0x125/0x1a0 [ 48.165380] do_exit+0x9cb/0x2a20 [ 48.168818] ? mm_update_next_owner+0x610/0x610 [ 48.173476] do_group_exit+0x100/0x2e0 [ 48.177349] SyS_exit_group+0x19/0x20 [ 48.181217] ? do_group_exit+0x2e0/0x2e0 [ 48.185463] do_syscall_64+0x19b/0x520 [ 48.189453] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.194623] RIP: 0033:0x440608 [ 48.197792] RSP: 002b:00007ffc749804f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.205484] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440608 [ 48.212831] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 48.220089] RBP: 00000000004c6950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.227493] R10: 0000000020004080 R11: 0000000000000246 R12: 0000000000000001 [ 48.235071] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 48.242347] [ 48.243961] Allocated by task 1791: [ 48.247577] __kasan_kmalloc.part.0+0x53/0xc0 [ 48.252058] kmem_cache_alloc+0xee/0x360 [ 48.256170] __alloc_skb+0xea/0x5c0 [ 48.259805] sk_stream_alloc_skb+0xf4/0x8a0 [ 48.264431] tcp_sendmsg_locked+0xf11/0x2f50 [ 48.268937] tcp_sendmsg+0x2b/0x40 [ 48.272457] inet_sendmsg+0x15b/0x520 [ 48.276245] sock_sendmsg+0xb7/0x100 [ 48.280061] SyS_sendto+0x1de/0x2f0 [ 48.283780] do_syscall_64+0x19b/0x520 [ 48.287646] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.292817] 0xffffffffffffffff [ 48.296083] [ 48.297791] Freed by task 1791: [ 48.301055] __kasan_slab_free+0x164/0x210 [ 48.305269] kmem_cache_free+0xd7/0x3b0 [ 48.309264] kfree_skbmem+0x84/0x110 [ 48.313130] tcp_remove_empty_skb+0x264/0x320 [ 48.317632] tcp_sendmsg_locked+0x1c09/0x2f50 [ 48.322120] tcp_sendmsg+0x2b/0x40 [ 48.325652] inet_sendmsg+0x15b/0x520 [ 48.329526] sock_sendmsg+0xb7/0x100 [ 48.333268] SyS_sendto+0x1de/0x2f0 [ 48.336884] do_syscall_64+0x19b/0x520 [ 48.340773] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.345957] 0xffffffffffffffff [ 48.349219] [ 48.350833] The buggy address belongs to the object at ffff8881d0461900 [ 48.350833] which belongs to the cache skbuff_fclone_cache of size 456 [ 48.364167] The buggy address is located 48 bytes inside of [ 48.364167] 456-byte region [ffff8881d0461900, ffff8881d0461ac8) [ 48.376217] The buggy address belongs to the page: [ 48.381246] page:ffffea0007411800 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 48.391352] flags: 0x4000000000010200(slab|head) [ 48.396271] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 48.404134] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 48.412162] page dumped because: kasan: bad access detected [ 48.417849] [ 48.419452] Memory state around the buggy address: [ 48.424399] ffff8881d0461800: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 48.431832] ffff8881d0461880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 48.439169] >ffff8881d0461900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.446509] ^ [ 48.451421] ffff8881d0461980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.458759] ffff8881d0461a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 48.466094] ================================================================== [ 48.473518] Disabling lock debugging due to kernel taint [ 48.479891] Kernel panic - not syncing: panic_on_warn set ... [ 48.479891] [ 48.487426] CPU: 0 PID: 1791 Comm: syz-executor341 Tainted: G B 4.14.145+ #0 [ 48.495831] Call Trace: [ 48.498417] dump_stack+0xca/0x134 [ 48.501946] panic+0x1ea/0x3d3 [ 48.505129] ? add_taint.cold+0x16/0x16 [ 48.509103] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.513505] ? ___preempt_schedule+0x16/0x18 [ 48.517908] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.522321] end_report+0x43/0x49 [ 48.525772] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.530165] __kasan_report.cold+0xd/0x41 [ 48.534347] ? kvm_guest_cpu_init+0x220/0x220 [ 48.538837] ? tcp_init_tso_segs+0x19d/0x1f0 [ 48.543240] tcp_init_tso_segs+0x19d/0x1f0 [ 48.547461] ? tcp_tso_segs+0x7b/0x1c0 [ 48.551501] tcp_write_xmit+0x15a/0x4730 [ 48.555644] ? memset+0x20/0x40 [ 48.559020] __tcp_push_pending_frames+0xa0/0x230 [ 48.563948] tcp_send_fin+0x154/0xbc0 [ 48.567842] tcp_close+0xc62/0xf40 [ 48.571381] inet_release+0xe9/0x1c0 [ 48.575082] __sock_release+0xd2/0x2c0 [ 48.579058] ? __sock_release+0x2c0/0x2c0 [ 48.583191] sock_close+0x15/0x20 [ 48.586767] __fput+0x25e/0x710 [ 48.590038] task_work_run+0x125/0x1a0 [ 48.593919] do_exit+0x9cb/0x2a20 [ 48.597388] ? mm_update_next_owner+0x610/0x610 [ 48.602046] do_group_exit+0x100/0x2e0 [ 48.606389] SyS_exit_group+0x19/0x20 [ 48.610169] ? do_group_exit+0x2e0/0x2e0 [ 48.614234] do_syscall_64+0x19b/0x520 [ 48.618108] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 48.623309] RIP: 0033:0x440608 [ 48.626570] RSP: 002b:00007ffc749804f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 48.634356] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440608 [ 48.641628] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 48.649054] RBP: 00000000004c6950 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 48.656450] R10: 0000000020004080 R11: 0000000000000246 R12: 0000000000000001 [ 48.663961] R13: 00000000006d95e0 R14: 0000000000000000 R15: 0000000000000000 [ 48.672271] Kernel Offset: 0x23e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 48.683192] Rebooting in 86400 seconds..