syzbot

kernel panic at /syzkaller/managers/main/kernel/kern/include/kref.h:68, from core 2: assertion failed: kref_refcnt(kref) > 0
Stack Backtrace on Core 2:
#01 [<0xffffffffc200a3ac>] in backtrace at src/kdebug.c:229
#02 [<0xffffffffc2009b3d>] in _panic at src/init.c:268
#03 [<     [inline]     >] in kref_put at include/kref.h:68
#03 [<0xffffffffc200ac1b>] in kfree at src/kmalloc.c:236
#04 [<0xffffffffc2031474>] in kstrdup at src/ns/chan.c:122
#05 [<0xffffffffc20755b3>] in conswrite at drivers/dev/cons.c:1246
#06 [<0xffffffffc207e11e>] in mntversion at drivers/dev/mnt.c:213
#07 [<0xffffffffc207f532>] in mntattach at drivers/dev/mnt.c:360
#08 [<0xffffffffc203f431>] in sysmount at src/ns/sysfile.c:530
#09 [<0xffffffffc2056581>] in sys_nmount at src/syscall.c:2196
#10 [<0xffffffffc2059f59>] in syscall at src/syscall.c:2465
#11 [<0xffffffffc205a124>] in run_local_syscall at src/syscall.c:2500
#12 [<0xffffffffc205a659>] in prep_syscalls at src/syscall.c:2520
#13 [<0xffffffffc20ac10a>] in sysenter_callwrapper at arch/x86/trap.c:854