[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 64.166213][ T26] audit: type=1800 audit(1575174734.701:25): pid=9031 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 64.186727][ T26] audit: type=1800 audit(1575174734.711:26): pid=9031 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 64.241637][ T26] audit: type=1800 audit(1575174734.711:27): pid=9031 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.15.223' (ECDSA) to the list of known hosts. 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 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 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 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 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 syzkaller login: [ 77.555805][ T9807] ------------[ cut here ]------------ [ 77.568666][ T9807] refcount_t: underflow; use-after-free. [ 77.587955][ T9807] WARNING: CPU: 1 PID: 9807 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 [ 77.598147][ T9807] Kernel panic - not syncing: panic_on_warn set ... [ 77.604861][ T9807] CPU: 1 PID: 9807 Comm: syz-executor293 Not tainted 5.4.0-syzkaller #0 [ 77.613522][ T9807] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 77.623860][ T9807] Call Trace: [ 77.627144][ T9807] dump_stack+0x197/0x210 [ 77.631465][ T9807] ? refcount_warn_saturate+0x190/0x1f0 [ 77.637083][ T9807] panic+0x2e3/0x75c [ 77.641057][ T9807] ? add_taint.cold+0x16/0x16 [ 77.645824][ T9807] ? __kasan_check_write+0x14/0x20 [ 77.650934][ T9807] ? __warn.cold+0x14/0x3e [ 77.655332][ T9807] ? __warn+0xd9/0x1cf [ 77.659397][ T9807] ? refcount_warn_saturate+0x1dc/0x1f0 [ 77.665183][ T9807] __warn.cold+0x2f/0x3e [ 77.669501][ T9807] ? refcount_warn_saturate+0x1dc/0x1f0 [ 77.675040][ T9807] report_bug+0x289/0x300 [ 77.679468][ T9807] do_error_trap+0x11b/0x200 [ 77.684062][ T9807] do_invalid_op+0x37/0x50 [ 77.688471][ T9807] ? refcount_warn_saturate+0x1dc/0x1f0 [ 77.694097][ T9807] invalid_op+0x23/0x30 [ 77.698436][ T9807] RIP: 0010:refcount_warn_saturate+0x1dc/0x1f0 [ 77.704587][ T9807] Code: e9 d8 fe ff ff 48 89 df e8 c1 5a 24 fe e9 85 fe ff ff e8 e7 08 e7 fd 48 c7 c7 a0 6f 4f 88 c6 05 60 b8 a4 06 01 e8 53 bd b7 fd <0f> 0b e9 ac fe ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 [ 77.725919][ T9807] RSP: 0018:ffff888093c97998 EFLAGS: 00010286 [ 77.732156][ T9807] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 77.740118][ T9807] RDX: 0000000000000000 RSI: ffffffff815e4316 RDI: ffffed1012792f25 [ 77.748195][ T9807] RBP: ffff888093c979a8 R08: ffff8880a04d4380 R09: ffffed1015d26621 [ 77.756155][ T9807] R10: ffffed1015d26620 R11: ffff8880ae933107 R12: 0000000000000003 [ 77.764117][ T9807] R13: 0000000000000000 R14: ffff8880a118d380 R15: ffff88809427e558 [ 77.772110][ T9807] ? vprintk_func+0x86/0x189 [ 77.776690][ T9807] ? refcount_warn_saturate+0x1dc/0x1f0 [ 77.782309][ T9807] smc_release+0x445/0x520 [ 77.786749][ T9807] __sock_release+0xce/0x280 [ 77.791327][ T9807] sock_close+0x1e/0x30 [ 77.795478][ T9807] __fput+0x2ff/0x890 [ 77.799458][ T9807] ? __sock_release+0x280/0x280 [ 77.804298][ T9807] ____fput+0x16/0x20 [ 77.808267][ T9807] task_work_run+0x145/0x1c0 [ 77.812950][ T9807] do_exit+0x8e7/0x2ef0 [ 77.817188][ T9807] ? mm_update_next_owner+0x7c0/0x7c0 [ 77.822751][ T9807] ? lock_downgrade+0x920/0x920 [ 77.827611][ T9807] ? _raw_spin_unlock_irq+0x23/0x80 [ 77.832881][ T9807] ? get_signal+0x392/0x24f0 [ 77.837457][ T9807] ? _raw_spin_unlock_irq+0x23/0x80 [ 77.842645][ T9807] do_group_exit+0x135/0x360 [ 77.847444][ T9807] get_signal+0x47c/0x24f0 [ 77.851953][ T9807] ? __local_bh_enable_ip+0x21d/0x270 [ 77.857330][ T9807] ? _raw_spin_unlock_bh+0x2c/0x30 [ 77.862443][ T9807] ? release_sock+0x156/0x1c0 [ 77.867108][ T9807] do_signal+0x87/0x1700 [ 77.871335][ T9807] ? __sys_connect_file+0xb1/0x2e0 [ 77.877650][ T9807] ? __ia32_sys_accept+0xb0/0xb0 [ 77.882600][ T9807] ? setup_sigcontext+0x7d0/0x7d0 [ 77.888412][ T9807] ? exit_to_usermode_loop+0x43/0x380 [ 77.893872][ T9807] ? do_fast_syscall_32+0xbbd/0xe16 [ 77.899058][ T9807] ? exit_to_usermode_loop+0x43/0x380 [ 77.905218][ T9807] ? lockdep_hardirqs_on+0x421/0x5e0 [ 77.910600][ T9807] ? trace_hardirqs_on+0x67/0x240 [ 77.915727][ T9807] exit_to_usermode_loop+0x286/0x380 [ 77.921099][ T9807] do_fast_syscall_32+0xbbd/0xe16 [ 77.926120][ T9807] entry_SYSENTER_compat+0x70/0x7f [ 77.931220][ T9807] RIP: 0023:0xf7f69a39 [ 77.935283][ T9807] Code: Bad RIP value. [ 77.939337][ T9807] RSP: 002b:00000000f7f441ec EFLAGS: 00000296 ORIG_RAX: 00000000000000f0 [ 77.947990][ T9807] RAX: fffffffffffffe00 RBX: 00000000080fb018 RCX: 0000000000000080 [ 77.956041][ T9807] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 [ 77.964118][ T9807] RBP: 0000000020000040 R08: 0000000000000000 R09: 0000000000000000 [ 77.972164][ T9807] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 77.980443][ T9807] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 77.990402][ T9807] Kernel Offset: disabled [ 77.994891][ T9807] Rebooting in 86400 seconds..