[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.760212] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.710162] random: sshd: uninitialized urandom read (32 bytes read) [ 17.980337] random: sshd: uninitialized urandom read (32 bytes read) [ 18.712345] random: sshd: uninitialized urandom read (32 bytes read) [ 18.846694] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.58' (ECDSA) to the list of known hosts. [ 24.304530] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 25.573283] ------------[ cut here ]------------ [ 25.578155] refcount_t: underflow; use-after-free. [ 25.583295] WARNING: CPU: 0 PID: 4455 at lib/refcount.c:187 refcount_sub_and_test+0x2e7/0x350 [ 25.591948] Kernel panic - not syncing: panic_on_warn set ... [ 25.591948] [ 25.599289] CPU: 0 PID: 4455 Comm: syz-executor034 Not tainted 4.18.0-rc3+ #58 [ 25.606630] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.615971] Call Trace: [ 25.618542] dump_stack+0x1c9/0x2b4 executing program [ 25.622170] ? dump_stack_print_info.cold.2+0x52/0x52 [ 25.627360] panic+0x238/0x4e7 [ 25.630542] ? add_taint.cold.5+0x16/0x16 [ 25.634686] ? __warn.cold.8+0x148/0x1ba [ 25.638748] ? __warn.cold.8+0x117/0x1ba [ 25.642801] ? refcount_sub_and_test+0x2e7/0x350 [ 25.647536] __warn.cold.8+0x163/0x1ba [ 25.651418] ? refcount_sub_and_test+0x2e7/0x350 [ 25.656167] report_bug+0x252/0x2d0 [ 25.659777] do_error_trap+0x1fc/0x4d0 [ 25.663643] ? math_error+0x3e0/0x3e0 [ 25.667437] ? vprintk_default+0x28/0x30 executing program executing program [ 25.671492] ? vprintk_func+0x81/0xe7 [ 25.675271] ? printk+0xa7/0xcf [ 25.678534] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 25.683371] do_invalid_op+0x1b/0x20 [ 25.687077] invalid_op+0x14/0x20 [ 25.690515] RIP: 0010:refcount_sub_and_test+0x2e7/0x350 [ 25.695849] Code: 89 de e8 4c 70 1c fe 84 db 74 07 31 db e9 46 ff ff ff e8 6c 6f 1c fe 48 c7 c7 e0 44 1a 88 c6 05 4a 3f 3a 06 01 e8 39 92 e7 fd <0f> 0b 31 db e9 25 ff ff ff 48 8b bd 28 ff ff ff 89 85 34 ff ff ff [ 25.715054] RSP: 0018:ffff8801b583f780 EFLAGS: 00010286 executing program executing program [ 25.720409] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 25.727666] RDX: 0000000000000000 RSI: ffffffff81631851 RDI: ffff8801b583f458 [ 25.734926] RBP: ffff8801b583f868 R08: ffff8801acd60040 R09: fffffbfff11f1220 [ 25.742186] R10: fffffbfff11f1220 R11: ffffffff88f89103 R12: 00000000ffffffff [ 25.749443] R13: ffff8801b583f840 R14: 0000000000000001 R15: 0000000000000000 [ 25.756715] ? vprintk_func+0x81/0xe7 [ 25.760516] ? refcount_inc_not_zero+0x2f0/0x2f0 [ 25.765267] ? trace_hardirqs_off+0xd/0x10 executing program [ 25.769483] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 25.774584] refcount_dec_and_test+0x1a/0x20 [ 25.778987] smap_release_sock+0x76/0x320 [ 25.783119] ? sock_map_alloc+0x410/0x410 [ 25.787247] ? __kasan_slab_free+0x131/0x170 [ 25.791647] ? trace_hardirqs_on+0xd/0x10 [ 25.795790] sock_hash_ctx_update_elem.isra.27+0x8cb/0x1690 [ 25.801490] ? sock_map_free+0x530/0x530 [ 25.805551] ? perf_trace_lock_acquire+0xeb/0x9a0 [ 25.810391] ? __fget+0x414/0x670 [ 25.813828] ? expand_files.part.8+0x9c0/0x9c0 [ 25.818396] ? lock_acquire+0x1e4/0x540 executing program executing program [ 25.822364] ? lock_acquire+0x1e4/0x540 [ 25.826337] sock_hash_update_elem+0x157/0x2f0 [ 25.830902] ? bpf_sock_hash_update+0x90/0x90 [ 25.835384] ? lock_release+0xa30/0xa30 [ 25.839366] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 25.844899] ? bpf_sock_hash_update+0x90/0x90 [ 25.849374] map_update_elem+0x5c4/0xc90 [ 25.853431] __x64_sys_bpf+0x32d/0x510 [ 25.857313] ? bpf_prog_get+0x20/0x20 [ 25.861101] do_syscall_64+0x1b9/0x820 [ 25.864970] ? syscall_return_slowpath+0x5e0/0x5e0 executing program [ 25.869896] ? syscall_return_slowpath+0x31d/0x5e0 [ 25.874821] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 25.879818] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 25.884657] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 25.889835] RIP: 0033:0x445ba9 [ 25.892998] Code: e8 8c be 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 11 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 25.912180] RSP: 002b:00007f8e7bfd2db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 executing program [ 25.919902] RAX: ffffffffffffffda RBX: 00000000006dbc3c RCX: 0000000000445ba9 [ 25.927159] RDX: 0000000000000020 RSI: 0000000020000180 RDI: 0000000000000002 [ 25.934418] RBP: 00000000006dbc38 R08: 0000000000000000 R09: 0000000000000000 [ 25.941681] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 25.948930] R13: 00007fffe69f94ef R14: 00007f8e7bfd39c0 R15: 0000000000000009 [ 25.956673] Dumping ftrace buffer: [ 25.960195] (ftrace buffer empty) [ 25.963892] Kernel Offset: disabled [ 25.967499] Rebooting in 86400 seconds..