[....] 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: [ 20.809604] random: sshd: uninitialized urandom read (32 bytes read) [ 21.058419] audit: type=1400 audit(1569037789.316:6): avc: denied { map } for pid=1765 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 [ 21.097840] random: sshd: uninitialized urandom read (32 bytes read) [ 21.621206] random: sshd: uninitialized urandom read (32 bytes read) [ 33.887790] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.55' (ECDSA) to the list of known hosts. [ 39.459655] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 39.553642] audit: type=1400 audit(1569037807.816:7): avc: denied { map } for pid=1783 comm="syz-executor561" path="/root/syz-executor561299943" 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 [ 39.557582] ================================================================== [ 39.587742] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 39.596528] Read of size 2 at addr ffff8881d607c7b0 by task syz-executor561/1783 [ 39.604047] [ 39.605662] CPU: 1 PID: 1783 Comm: syz-executor561 Not tainted 4.14.145+ #0 [ 39.612738] Call Trace: [ 39.615312] dump_stack+0xca/0x134 [ 39.618834] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.623339] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.627748] print_address_description+0x60/0x226 [ 39.632598] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.637009] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.641421] __kasan_report.cold+0x1a/0x41 [ 39.645663] ? kvm_guest_cpu_init+0x220/0x220 [ 39.650254] ? tcp_init_tso_segs+0x19d/0x1f0 [ 39.655687] tcp_init_tso_segs+0x19d/0x1f0 [ 39.659906] ? tcp_tso_segs+0x7b/0x1c0 [ 39.664647] tcp_write_xmit+0x15a/0x4730 [ 39.668716] ? ip6_mtu+0x206/0x330 [ 39.672246] ? lock_downgrade+0x5d0/0x5d0 [ 39.676981] ? lock_acquire+0x12b/0x360 [ 39.680986] __tcp_push_pending_frames+0xa0/0x230 [ 39.685812] tcp_send_fin+0x154/0xbc0 [ 39.689597] tcp_close+0xc62/0xf40 [ 39.693129] ? lock_acquire+0x12b/0x360 [ 39.697086] ? __sock_release+0x86/0x2c0 [ 39.701222] inet_release+0xe9/0x1c0 [ 39.704918] inet6_release+0x4c/0x70 [ 39.708648] __sock_release+0xd2/0x2c0 [ 39.712522] ? __sock_release+0x2c0/0x2c0 [ 39.716670] sock_close+0x15/0x20 [ 39.720127] __fput+0x25e/0x710 [ 39.723405] task_work_run+0x125/0x1a0 [ 39.727286] do_exit+0x9cb/0x2a20 [ 39.730812] ? mm_update_next_owner+0x610/0x610 [ 39.735559] do_group_exit+0x100/0x2e0 [ 39.739430] SyS_exit_group+0x19/0x20 [ 39.743211] ? do_group_exit+0x2e0/0x2e0 [ 39.747252] do_syscall_64+0x19b/0x520 [ 39.751129] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.756302] RIP: 0033:0x43ee48 [ 39.759487] RSP: 002b:00007ffd14307bb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 39.767179] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee48 [ 39.774536] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 39.781790] RBP: 00000000004be648 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 39.789307] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 39.796567] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 39.803921] [ 39.805621] Allocated by task 1783: [ 39.809246] __kasan_kmalloc.part.0+0x53/0xc0 [ 39.813723] kmem_cache_alloc+0xee/0x360 [ 39.817764] __alloc_skb+0xea/0x5c0 [ 39.821437] sk_stream_alloc_skb+0xf4/0x8a0 [ 39.825779] tcp_sendmsg_locked+0xf11/0x2f50 [ 39.830175] tcp_sendmsg+0x2b/0x40 [ 39.833696] inet_sendmsg+0x15b/0x520 [ 39.837495] sock_sendmsg+0xb7/0x100 [ 39.841190] SyS_sendto+0x1de/0x2f0 [ 39.844799] do_syscall_64+0x19b/0x520 [ 39.848664] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.853928] 0xffffffffffffffff [ 39.857247] [ 39.858855] Freed by task 1783: [ 39.862119] __kasan_slab_free+0x164/0x210 [ 39.866332] kmem_cache_free+0xd7/0x3b0 [ 39.870288] kfree_skbmem+0x84/0x110 [ 39.873981] tcp_remove_empty_skb+0x264/0x320 [ 39.878452] tcp_sendmsg_locked+0x1c09/0x2f50 [ 39.883004] tcp_sendmsg+0x2b/0x40 [ 39.886651] inet_sendmsg+0x15b/0x520 [ 39.890433] sock_sendmsg+0xb7/0x100 [ 39.894136] SyS_sendto+0x1de/0x2f0 [ 39.897744] do_syscall_64+0x19b/0x520 [ 39.901613] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 39.906780] 0xffffffffffffffff [ 39.910163] [ 39.911771] The buggy address belongs to the object at ffff8881d607c780 [ 39.911771] which belongs to the cache skbuff_fclone_cache of size 456 [ 39.925199] The buggy address is located 48 bytes inside of [ 39.925199] 456-byte region [ffff8881d607c780, ffff8881d607c948) [ 39.937106] The buggy address belongs to the page: [ 39.942022] page:ffffea0007581f00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 39.951982] flags: 0x4000000000010200(slab|head) [ 39.956718] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 39.964601] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 39.972459] page dumped because: kasan: bad access detected [ 39.978161] [ 39.979783] Memory state around the buggy address: [ 39.984694] ffff8881d607c680: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 39.992031] ffff8881d607c700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 39.999400] >ffff8881d607c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.006739] ^ [ 40.011646] ffff8881d607c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.018997] ffff8881d607c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.026346] ================================================================== [ 40.033689] Disabling lock debugging due to kernel taint [ 40.039199] Kernel panic - not syncing: panic_on_warn set ... [ 40.039199] [ 40.046559] CPU: 1 PID: 1783 Comm: syz-executor561 Tainted: G B 4.14.145+ #0 [ 40.055075] Call Trace: [ 40.057650] dump_stack+0xca/0x134 [ 40.061176] panic+0x1ea/0x3d3 [ 40.064355] ? add_taint.cold+0x16/0x16 [ 40.068319] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.072724] ? ___preempt_schedule+0x16/0x18 [ 40.077121] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.081509] end_report+0x43/0x49 [ 40.084963] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.089535] __kasan_report.cold+0xd/0x41 [ 40.093853] ? kvm_guest_cpu_init+0x220/0x220 [ 40.098336] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.102726] tcp_init_tso_segs+0x19d/0x1f0 [ 40.106954] ? tcp_tso_segs+0x7b/0x1c0 [ 40.110834] tcp_write_xmit+0x15a/0x4730 [ 40.114875] ? ip6_mtu+0x206/0x330 [ 40.118393] ? lock_downgrade+0x5d0/0x5d0 [ 40.122624] ? lock_acquire+0x12b/0x360 [ 40.126583] __tcp_push_pending_frames+0xa0/0x230 [ 40.131494] tcp_send_fin+0x154/0xbc0 [ 40.135277] tcp_close+0xc62/0xf40 [ 40.138882] ? lock_acquire+0x12b/0x360 [ 40.142838] ? __sock_release+0x86/0x2c0 [ 40.146886] inet_release+0xe9/0x1c0 [ 40.150647] inet6_release+0x4c/0x70 [ 40.154369] __sock_release+0xd2/0x2c0 [ 40.158429] ? __sock_release+0x2c0/0x2c0 [ 40.162591] sock_close+0x15/0x20 [ 40.166223] __fput+0x25e/0x710 [ 40.169574] task_work_run+0x125/0x1a0 [ 40.173447] do_exit+0x9cb/0x2a20 [ 40.176920] ? mm_update_next_owner+0x610/0x610 [ 40.181591] do_group_exit+0x100/0x2e0 [ 40.185650] SyS_exit_group+0x19/0x20 [ 40.189522] ? do_group_exit+0x2e0/0x2e0 [ 40.193583] do_syscall_64+0x19b/0x520 [ 40.197495] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.197501] RIP: 0033:0x43ee48 [ 40.197507] RSP: 002b:00007ffd14307bb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 40.213588] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee48 [ 40.221072] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 40.228543] RBP: 00000000004be648 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 40.228547] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 40.228550] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 40.229774] Kernel Offset: 0x5600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 40.262618] Rebooting in 86400 seconds..