[....] Starting OpenBSD Secure Shell server: sshd[ 10.594078] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 40.287891] random: sshd: uninitialized urandom read (32 bytes read) [ 40.573438] audit: type=1400 audit(1569072759.917:6): 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 [ 40.645962] random: sshd: uninitialized urandom read (32 bytes read) [ 41.196739] random: sshd: uninitialized urandom read (32 bytes read) [ 54.277876] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 59.704839] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 59.804444] audit: type=1400 audit(1569072779.147:7): avc: denied { map } for pid=1797 comm="syz-executor404" path="/root/syz-executor404605033" 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 [ 59.807679] ================================================================== [ 59.838013] BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 [ 59.844777] Read of size 2 at addr ffff8881cfd61bb0 by task syz-executor404/1797 [ 59.852288] [ 59.853897] CPU: 0 PID: 1797 Comm: syz-executor404 Not tainted 4.14.145+ #0 [ 59.860972] Call Trace: [ 59.863541] dump_stack+0xca/0x134 [ 59.867058] ? tcp_init_tso_segs+0x19d/0x1f0 [ 59.871443] ? tcp_init_tso_segs+0x19d/0x1f0 [ 59.875831] print_address_description+0x60/0x226 [ 59.880665] ? tcp_init_tso_segs+0x19d/0x1f0 [ 59.885051] ? tcp_init_tso_segs+0x19d/0x1f0 [ 59.889435] __kasan_report.cold+0x1a/0x41 [ 59.893653] ? kvm_guest_cpu_init+0x220/0x220 [ 59.898123] ? tcp_init_tso_segs+0x19d/0x1f0 [ 59.902518] tcp_init_tso_segs+0x19d/0x1f0 [ 59.906730] ? tcp_tso_segs+0x7b/0x1c0 [ 59.910598] tcp_write_xmit+0x15a/0x4730 [ 59.914643] ? memset+0x20/0x40 [ 59.917906] __tcp_push_pending_frames+0xa0/0x230 [ 59.922743] tcp_send_fin+0x154/0xbc0 [ 59.926529] tcp_close+0xc62/0xf40 [ 59.930062] inet_release+0xe9/0x1c0 [ 59.933761] __sock_release+0xd2/0x2c0 [ 59.937630] ? __sock_release+0x2c0/0x2c0 [ 59.941753] sock_close+0x15/0x20 [ 59.945184] __fput+0x25e/0x710 [ 59.948448] task_work_run+0x125/0x1a0 [ 59.952335] do_exit+0x9cb/0x2a20 [ 59.955772] ? mm_update_next_owner+0x610/0x610 [ 59.960428] do_group_exit+0x100/0x2e0 [ 59.964314] SyS_exit_group+0x19/0x20 [ 59.968090] ? do_group_exit+0x2e0/0x2e0 [ 59.972128] do_syscall_64+0x19b/0x520 [ 59.976010] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 59.981178] RIP: 0033:0x43ee08 [ 59.984346] RSP: 002b:00007ffffe3fe6e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 59.992043] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 59.999342] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 60.006602] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 60.013855] R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000001 [ 60.021105] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 60.028367] [ 60.029989] Allocated by task 1797: [ 60.033601] __kasan_kmalloc.part.0+0x53/0xc0 [ 60.038074] kmem_cache_alloc+0xee/0x360 [ 60.042116] __alloc_skb+0xea/0x5c0 [ 60.045734] sk_stream_alloc_skb+0xf4/0x8a0 [ 60.050045] tcp_sendmsg_locked+0xf11/0x2f50 [ 60.054441] tcp_sendmsg+0x2b/0x40 [ 60.057961] inet_sendmsg+0x15b/0x520 [ 60.061750] sock_sendmsg+0xb7/0x100 [ 60.065450] SyS_sendto+0x1de/0x2f0 [ 60.069209] do_syscall_64+0x19b/0x520 [ 60.073098] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 60.078270] 0xffffffffffffffff [ 60.081539] [ 60.083159] Freed by task 1797: [ 60.086418] __kasan_slab_free+0x164/0x210 [ 60.090635] kmem_cache_free+0xd7/0x3b0 [ 60.094588] kfree_skbmem+0x84/0x110 [ 60.098280] tcp_remove_empty_skb+0x264/0x320 [ 60.102769] tcp_sendmsg_locked+0x1c09/0x2f50 [ 60.107239] tcp_sendmsg+0x2b/0x40 [ 60.110776] inet_sendmsg+0x15b/0x520 [ 60.114570] sock_sendmsg+0xb7/0x100 [ 60.118282] SyS_sendto+0x1de/0x2f0 [ 60.121903] do_syscall_64+0x19b/0x520 [ 60.125766] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 60.130933] 0xffffffffffffffff [ 60.134202] [ 60.135806] The buggy address belongs to the object at ffff8881cfd61b80 [ 60.135806] which belongs to the cache skbuff_fclone_cache of size 456 [ 60.149129] The buggy address is located 48 bytes inside of [ 60.149129] 456-byte region [ffff8881cfd61b80, ffff8881cfd61d48) [ 60.160893] The buggy address belongs to the page: [ 60.165797] page:ffffea00073f5800 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 [ 60.175741] flags: 0x4000000000010200(slab|head) [ 60.180478] raw: 4000000000010200 0000000000000000 0000000000000000 00000001000c000c [ 60.188334] raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000 [ 60.196190] page dumped because: kasan: bad access detected [ 60.201898] [ 60.203516] Memory state around the buggy address: [ 60.208445] ffff8881cfd61a80: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc [ 60.215791] ffff8881cfd61b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 60.223139] >ffff8881cfd61b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 60.230486] ^ [ 60.235391] ffff8881cfd61c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 60.242740] ffff8881cfd61c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 60.250075] ================================================================== [ 60.257415] Disabling lock debugging due to kernel taint [ 60.262933] Kernel panic - not syncing: panic_on_warn set ... [ 60.262933] [ 60.270289] CPU: 0 PID: 1797 Comm: syz-executor404 Tainted: G B 4.14.145+ #0 [ 60.278581] Call Trace: [ 60.281164] dump_stack+0xca/0x134 [ 60.284701] panic+0x1ea/0x3d3 [ 60.287868] ? add_taint.cold+0x16/0x16 [ 60.291832] ? tcp_init_tso_segs+0x19d/0x1f0 [ 60.296253] ? ___preempt_schedule+0x16/0x18 [ 60.300647] ? tcp_init_tso_segs+0x19d/0x1f0 [ 60.305035] end_report+0x43/0x49 [ 60.308466] ? tcp_init_tso_segs+0x19d/0x1f0 [ 60.312849] __kasan_report.cold+0xd/0x41 [ 60.316980] ? kvm_guest_cpu_init+0x220/0x220 [ 60.321456] ? tcp_init_tso_segs+0x19d/0x1f0 [ 60.325855] tcp_init_tso_segs+0x19d/0x1f0 [ 60.330073] ? tcp_tso_segs+0x7b/0x1c0 [ 60.333942] tcp_write_xmit+0x15a/0x4730 [ 60.337982] ? memset+0x20/0x40 [ 60.341258] __tcp_push_pending_frames+0xa0/0x230 [ 60.346077] tcp_send_fin+0x154/0xbc0 [ 60.349856] tcp_close+0xc62/0xf40 [ 60.353375] inet_release+0xe9/0x1c0 [ 60.357065] __sock_release+0xd2/0x2c0 [ 60.360929] ? __sock_release+0x2c0/0x2c0 [ 60.365136] sock_close+0x15/0x20 [ 60.368577] __fput+0x25e/0x710 [ 60.371839] task_work_run+0x125/0x1a0 [ 60.375704] do_exit+0x9cb/0x2a20 [ 60.379136] ? mm_update_next_owner+0x610/0x610 [ 60.383788] do_group_exit+0x100/0x2e0 [ 60.387651] SyS_exit_group+0x19/0x20 [ 60.391442] ? do_group_exit+0x2e0/0x2e0 [ 60.395479] do_syscall_64+0x19b/0x520 [ 60.399343] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 60.404526] RIP: 0033:0x43ee08 [ 60.407705] RSP: 002b:00007ffffe3fe6e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 60.415390] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee08 [ 60.422638] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 60.429886] RBP: 00000000004be608 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 60.437131] R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000001 [ 60.444390] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 60.452324] Kernel Offset: 0x17e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 60.463231] Rebooting in 86400 seconds..