[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.316220] random: sshd: uninitialized urandom read (32 bytes read, 33 bits of entropy available) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.078141] random: sshd: uninitialized urandom read (32 bytes read, 40 bits of entropy available) [ 26.453299] random: sshd: uninitialized urandom read (32 bytes read, 40 bits of entropy available) [ 27.177636] random: sshd: uninitialized urandom read (32 bytes read, 74 bits of entropy available) [ 27.362643] random: sshd: uninitialized urandom read (32 bytes read, 77 bits of entropy available) Warning: Permanently added '10.128.0.55' (ECDSA) to the list of known hosts. [ 32.995729] random: sshd: uninitialized urandom read (32 bytes read, 82 bits of entropy available) executing program [ 33.082347] BUG: using __this_cpu_add() in preemptible [00000000] code: syz-executor889/3798 [ 33.091099] caller is __this_cpu_preempt_check+0x1c/0x20 [ 33.096551] CPU: 0 PID: 3798 Comm: syz-executor889 Not tainted 4.4.148-gf057ff9 #81 [ 33.104321] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.113652] 0000000000000000 69e68120c3356646 ffff8801d979f5f0 ffffffff81e1448d [ 33.121653] 0000000000000000 ffffffff83c154c0 ffffffff83f0d440 ffff8801ca6ae000 [ 33.129689] 0000000000000003 ffff8801d979f630 ffffffff81ebdd33 ffff8801d077abbc [ 33.137691] Call Trace: [ 33.140272] [] dump_stack+0xc1/0x124 [ 33.145615] [] check_preemption_disabled.cold.0+0x7f/0x8b [ 33.152783] [] __this_cpu_preempt_check+0x1c/0x20 [ 33.159276] [] tcp_try_coalesce+0x22a/0x4c0 [ 33.165250] [] ? tcp_parse_options+0x970/0x970 [ 33.171457] [] tcp_queue_rcv+0x127/0x6f0 [ 33.177160] [] tcp_send_rcvq+0x3a6/0x470 [ 33.182853] [] ? tcp_rcv_established+0x1fe0/0x1fe0 [ 33.189435] [] ? do_softirq.part.16+0x20/0x60 [ 33.195589] [] ? trace_hardirqs_on_caller+0x38b/0x590 [ 33.202416] [] ? lock_sock_nested+0x90/0x120 [ 33.208479] [] ? trace_hardirqs_on+0xd/0x10 [ 33.214483] [] ? __local_bh_enable_ip+0x6a/0xd0 [ 33.220805] [] tcp_sendmsg+0x23ec/0x2b10 [ 33.226495] [] ? sock_has_perm+0x29f/0x400 [ 33.232387] [] ? tcp_sendpage+0x17c0/0x17c0 [ 33.238349] [] ? inet_sendmsg+0x143/0x4d0 [ 33.244123] [] inet_sendmsg+0x203/0x4d0 [ 33.249723] [] ? inet_sendmsg+0x73/0x4d0 [ 33.255410] [] ? inet_recvmsg+0x4c0/0x4c0 [ 33.261190] [] sock_sendmsg+0xcc/0x110 [ 33.266704] [] ___sys_sendmsg+0x441/0x880 [ 33.272481] [] ? copy_msghdr_from_user+0x550/0x550 [ 33.279056] [] ? debug_check_no_locks_freed+0x210/0x210 [ 33.286066] [] ? tcp_v4_connect+0x1003/0x1890 [ 33.292208] [] ? debug_lockdep_rcu_enabled+0x77/0x90 [ 33.298940] [] ? __fget_light+0x9f/0x1f0 [ 33.304628] [] ? __fdget+0x18/0x20 [ 33.309839] [] __sys_sendmmsg+0x12e/0x2e0 [ 33.315619] [] ? SyS_sendmsg+0x50/0x50 [ 33.321222] [] ? inet_stream_connect+0x78/0xa0 [ 33.327428] [] ? SYSC_connect+0x22a/0x300 [ 3