[....] 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: [ 20.392462] random: sshd: uninitialized urandom read (32 bytes read) [ 20.576412] audit: type=1400 audit(1569082642.915:6): avc: denied { map } for pid=1757 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 [ 20.621634] random: sshd: uninitialized urandom read (32 bytes read) [ 21.143952] random: sshd: uninitialized urandom read (32 bytes read) [ 34.977081] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.142' (ECDSA) to the list of known hosts. [ 40.404771] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 40.502003] audit: type=1400 audit(1569082662.845:7): avc: denied { map } for pid=1781 comm="syz-executor244" path="/root/syz-executor244395951" 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 [ 40.515167] ================================================================== [ 40.536364] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 40.543113] Read of size 2 at addr ffff8881d693a2b0 by task syz-executor244/1781 [ 40.550710] [ 40.552318] CPU: 0 PID: 1781 Comm: syz-executor244 Not tainted 4.14.145+ #0 [ 40.560449] Call Trace: [ 40.563020] dump_stack+0xca/0x134 [ 40.566542] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.570930] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.575325] print_address_description+0x60/0x226 [ 40.580146] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.584548] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.589003] __kasan_report.cold+0x1a/0x41 [ 40.593246] ? kvm_guest_cpu_init+0x220/0x220 [ 40.597740] ? tcp_init_tso_segs+0x19d/0x1f0 [ 40.602139] tcp_init_tso_segs+0x19d/0x1f0 [ 40.606381] ? tcp_tso_segs+0x7b/0x1c0 [ 40.610250] tcp_write_xmit+0x15a/0x4730 [ 40.614356] ? ip6_mtu+0x206/0x330 [ 40.617909] ? lock_downgrade+0x5d0/0x5d0 [ 40.622042] ? lock_acquire+0x12b/0x360 [ 40.626007] __tcp_push_pending_frames+0xa0/0x230 [ 40.630872] tcp_send_fin+0x154/0xbc0 [ 40.634667] tcp_close+0xc62/0xf40 [ 40.638212] ? lock_acquire+0x12b/0x360 [ 40.642184] ? __sock_release+0x86/0x2c0 [ 40.646237] inet_release+0xe9/0x1c0 [ 40.649950] inet6_release+0x4c/0x70 [ 40.653663] __sock_release+0xd2/0x2c0 [ 40.657547] ? __sock_release+0x2c0/0x2c0 [ 40.661770] sock_close+0x15/0x20 [ 40.665220] __fput+0x25e/0x710 [ 40.668512] task_work_run+0x125/0x1a0 [ 40.672690] do_exit+0x9cb/0x2a20 [ 40.676930] ? mm_update_next_owner+0x610/0x610 [ 40.681601] do_group_exit+0x100/0x2e0 [ 40.685471] SyS_exit_group+0x19/0x20 [ 40.689248] ? do_group_exit+0x2e0/0x2e0 [ 40.693287] do_syscall_64+0x19b/0x520 [ 40.697191] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.702363] RIP: 0033:0x43ee48 [ 40.705538] RSP: 002b:00007fffc21c4ed8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 40.713227] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee48 [ 40.720580] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 40.727840] RBP: 00000000004be648 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 40.735095] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 40.742351] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 40.749617] [ 40.751228] Allocated by task 1781: [ 40.754840] __kasan_kmalloc.part.0+0x53/0xc0 [ 40.759322] kmem_cache_alloc+0xee/0x360 [ 40.763447] __alloc_skb+0xea/0x5c0 [ 40.767081] sk_stream_alloc_skb+0xf4/0x8a0 [ 40.771384] tcp_sendmsg_locked+0xf11/0x2f50 [ 40.775792] tcp_sendmsg+0x2b/0x40 [ 40.779320] inet_sendmsg+0x15b/0x520 [ 40.783133] sock_sendmsg+0xb7/0x100 [ 40.786822] SyS_sendto+0x1de/0x2f0 [ 40.790428] do_syscall_64+0x19b/0x520 [ 40.794309] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.799478] 0xffffffffffffffff [ 40.802755] [ 40.804367] Freed by task 1781: [ 40.807630] __kasan_slab_free+0x164/0x210 [ 40.811842] kmem_cache_free+0xd7/0x3b0 [ 40.815812] kfree_skbmem+0x84/0x110 [ 40.819514] tcp_remove_empty_skb+0x264/0x320 [ 40.824000] tcp_sendmsg_locked+0x1c09/0x2f50 [ 40.828470] tcp_sendmsg+0x2b/0x40 [ 40.831990] inet_sendmsg+0x15b/0x520 [ 40.835778] sock_sendmsg+0xb7/0x100 [ 40.839571] SyS_sendto+0x1de/0x2f0 [ 40.843189] do_syscall_64+0x19b/0x520 [ 40.847079] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 40.852342] 0xffffffffffffffff [ 40.855597] [ 40.857213] The buggy address belongs to the object at ffff8881d693a280 [ 40.857213] which belongs to the cache skbuff_fclone_cache of size 456 [ 40.870552] The buggy address is located 48 bytes inside of [ 40.870552] 456-byte region [ffff8881d693a280, ffff8881d693a448) [ 40.882316] The buggy address belongs to the page: [ 40.887224] page:ffffea00075a4e80 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 40.897188] flags: 0x4000000000010200(slab|head) [ 40.901984] raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c [ 40.909860] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 40.917721] page dumped because: kasan: bad access detected [ 40.923416] [ 40.925019] Memory state around the buggy address: [ 40.929931] ffff8881d693a180: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 40.937266] ffff8881d693a200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 40.944608] >ffff8881d693a280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.951952] ^ [ 40.956855] ffff8881d693a300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.964198] ffff8881d693a380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 40.971544] ================================================================== [ 40.978895] Disabling lock debugging due to kernel taint [ 40.985950] Kernel panic - not syncing: panic_on_warn set ... [ 40.985950] [ 40.993413] CPU: 0 PID: 1781 Comm: syz-executor244 Tainted: G B 4.14.145+ #0 [ 41.001707] Call Trace: [ 41.004288] dump_stack+0xca/0x134 [ 41.007806] panic+0x1ea/0x3d3 [ 41.010973] ? add_taint.cold+0x16/0x16 [ 41.014938] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.019329] end_report+0x43/0x49 [ 41.022768] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.027150] __kasan_report.cold+0xd/0x41 [ 41.031283] ? kvm_guest_cpu_init+0x220/0x220 [ 41.035765] ? tcp_init_tso_segs+0x19d/0x1f0 [ 41.040187] tcp_init_tso_segs+0x19d/0x1f0 [ 41.040193] ? tcp_tso_segs+0x7b/0x1c0 [ 41.040201] tcp_write_xmit+0x15a/0x4730 [ 41.040212] ? ip6_mtu+0x206/0x330 [ 41.040220] ? lock_downgrade+0x5d0/0x5d0 [ 41.040226] ? lock_acquire+0x12b/0x360 [ 41.040240] __tcp_push_pending_frames+0xa0/0x230 [ 41.040247] tcp_send_fin+0x154/0xbc0 [ 41.040258] tcp_close+0xc62/0xf40 [ 41.040263] ? lock_acquire+0x12b/0x360 [ 41.040271] ? __sock_release+0x86/0x2c0 [ 41.040281] inet_release+0xe9/0x1c0 [ 41.040291] inet6_release+0x4c/0x70 [ 41.040298] __sock_release+0xd2/0x2c0 [ 41.040306] ? __sock_release+0x2c0/0x2c0 [ 41.040312] sock_close+0x15/0x20 [ 41.040320] __fput+0x25e/0x710 [ 41.040333] task_work_run+0x125/0x1a0 [ 41.040345] do_exit+0x9cb/0x2a20 [ 41.040358] ? mm_update_next_owner+0x610/0x610 [ 41.040375] do_group_exit+0x100/0x2e0 [ 41.040384] SyS_exit_group+0x19/0x20 [ 41.040390] ? do_group_exit+0x2e0/0x2e0 [ 41.040396] do_syscall_64+0x19b/0x520 [ 41.040409] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 41.040415] RIP: 0033:0x43ee48 [ 41.040419] RSP: 002b:00007fffc21c4ed8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 41.040426] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee48 [ 41.040430] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 41.040434] RBP: 00000000004be648 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 41.040438] R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001 [ 41.040442] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 41.041431] Kernel Offset: 0x29600000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 41.198306] Rebooting in 86400 seconds..