[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.846058] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.873647] random: sshd: uninitialized urandom read (32 bytes read) [ 20.228193] random: sshd: uninitialized urandom read (32 bytes read) [ 20.918783] random: sshd: uninitialized urandom read (32 bytes read) [ 21.049577] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. [ 26.525573] 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 [ 27.176588] ------------[ cut here ]------------ [ 27.181382] refcount_t: underflow; use-after-free. [ 27.186433] WARNING: CPU: 0 PID: 4457 at lib/refcount.c:187 refcount_sub_and_test+0x2e7/0x350 [ 27.195069] Kernel panic - not syncing: panic_on_warn set ... [ 27.195069] [ 27.202408] CPU: 0 PID: 4457 Comm: syz-executor415 Not tainted 4.18.0-rc3+ #49 [ 27.209740] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.219069] Call Trace: [ 27.221641] dump_stack+0x1c9/0x2b4 [ 27.225248] ? dump_stack_print_info.cold.2+0x52/0x52 [ 27.230418] panic+0x238/0x4e7 [ 27.233586] ? add_taint.cold.5+0x16/0x16 [ 27.237721] ? __warn.cold.8+0x148/0x1ba [ 27.241757] ? __warn.cold.8+0x117/0x1ba [ 27.245804] ? refcount_sub_and_test+0x2e7/0x350 [ 27.250537] __warn.cold.8+0x163/0x1ba [ 27.254407] ? refcount_sub_and_test+0x2e7/0x350 [ 27.259140] report_bug+0x252/0x2d0 [ 27.262746] do_error_trap+0x1fc/0x4d0 [ 27.266607] ? math_error+0x3e0/0x3e0 [ 27.270386] ? vprintk_default+0x28/0x30 [ 27.274422] ? vprintk_func+0x81/0xe7 [ 27.278196] ? printk+0xa7/0xcf [ 27.281464] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.286283] do_invalid_op+0x1b/0x20 [ 27.289972] invalid_op+0x14/0x20 [ 27.293413] RIP: 0010:refcount_sub_and_test+0x2e7/0x350 [ 27.298744] Code: 89 de e8 ec c0 1c fe 84 db 74 07 31 db e9 46 ff ff ff e8 0c c0 1c fe 48 c7 c7 20 42 1a 88 c6 05 cd 82 3a 06 01 e8 d9 e2 e7 fd <0f> 0b 31 db e9 25 ff ff ff 48 8b bd 28 ff ff ff 89 85 34 ff ff ff [ 27.317856] RSP: 0018:ffff8801ac707780 EFLAGS: 00010286 [ 27.323194] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 27.330438] RDX: 0000000000000000 RSI: ffffffff81631851 RDI: ffff8801ac707458 [ 27.337684] RBP: ffff8801ac707868 R08: ffff8801d90f2040 R09: fffffbfff11f1220 [ 27.344929] R10: fffffbfff11f1220 R11: ffffffff88f89103 R12: 00000000ffffffff [ 27.352175] R13: ffff8801ac707840 R14: 0000000000000001 R15: ffff8801b7b81c00 [ 27.359437] ? vprintk_func+0x81/0xe7 [ 27.363228] ? refcount_inc_not_zero+0x2f0/0x2f0 [ 27.367972] ? trace_hardirqs_off+0xd/0x10 [ 27.372184] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 27.377268] refcount_dec_and_test+0x1a/0x20 [ 27.381659] smap_release_sock+0x76/0x320 [ 27.385785] ? sock_map_alloc+0x410/0x410 [ 27.389912] ? __kasan_slab_free+0x131/0x170 [ 27.394311] ? trace_hardirqs_on+0xd/0x10 [ 27.398441] sock_hash_ctx_update_elem.isra.27+0x8cb/0x1690 [ 27.404136] ? sock_map_free+0x530/0x530 [ 27.408175] ? save_stack+0xa9/0xd0 [ 27.411778] ? __fget+0x414/0x670 [ 27.415207] ? expand_files.part.8+0x9c0/0x9c0 [ 27.419769] ? lock_acquire+0x1e4/0x540 [ 27.423719] ? fs_reclaim_acquire+0x20/0x20 [ 27.428017] ? lock_acquire+0x1e4/0x540 [ 27.431968] sock_hash_update_elem+0x157/0x2f0 [ 27.436529] ? bpf_sock_hash_update+0x90/0x90 [ 27.441005] ? lock_release+0xa30/0xa30 [ 27.444958] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 27.450471] ? bpf_sock_hash_update+0x90/0x90 [ 27.454940] map_update_elem+0x5c4/0xc90 [ 27.458977] __x64_sys_bpf+0x32d/0x510 [ 27.462839] ? bpf_prog_get+0x20/0x20 [ 27.466623] do_syscall_64+0x1b9/0x820 [ 27.470485] ? syscall_return_slowpath+0x5e0/0x5e0 [ 27.475390] ? syscall_return_slowpath+0x31d/0x5e0 [ 27.480301] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 27.485293] ? prepare_exit_to_usermode+0x291/0x3b0 [ 27.490287] ? perf_trace_sys_enter+0xb10/0xb10 [ 27.494933] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.499754] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 27.504917] RIP: 0033:0x445cd9 [ 27.508083] Code: e8 7c b7 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 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 27.527194] RSP: 002b:00007f0f93763da8 EFLAGS: 00000297 ORIG_RAX: 0000000000000141 [ 27.534876] RAX: ffffffffffffffda RBX: 00000000006dac7c RCX: 0000000000445cd9 [ 27.542127] RDX: 0000000000000020 RSI: 0000000020000000 RDI: 0000000000000002 [ 27.549371] RBP: 00000000006dac78 R08: 0000000000000000 R09: 0000000000000000 [ 27.556613] R10: 0000000000000000 R11: 0000000000000297 R12: 7a79732f7570632e [ 27.563856] R13: 70756f7267632f2e R14: 702e70756f726763 R15: 0000000000000015 [ 27.571588] Dumping ftrace buffer: [ 27.575102] (ftrace buffer empty) [ 27.578787] Kernel Offset: disabled [ 27.582390] Rebooting in 86400 seconds..