kernel panic: (cclose ADDR

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 6f34e34a70a3 Add backtrace helpers
git tree: https://github.com/akaros/akaros.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=154e75c2400000
kernel config: https://syzkaller.appspot.com/x/.config?x=efef8cf2939304d3
dashboard link: https://syzkaller.appspot.com/bug?extid=7e76cb0448f119f2992b
compiler:

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7e76cb...@syzkaller.appspotmail.com

kernel panic at kern/src/ns/chan.c:331, from core 3: (cclose
0x0000000000000000
Stack Backtrace on Core 3:
���#01 [<0xffffffffc200a30c>] in backtrace
#0 �'n �;W� %2 [<0xffffffffc2009b0d>] in _panic
�#03 [<0xffffffffc203190a>] in cclose
{#04 [<0xffffffffc20332e9>] in walk_symlink
�#05 [<0xffffffffc20332d4>] in walk_symlink
����a+� `#06 [<0xffffffffc20332d4>] in �walk_symlink
#07 [<0xffffffffc20332d4>] in walk_symlink
�(w q���zw�u#08 [<0xffffffffc20332d4>] in walk_symlink
#09 [<0xffffffffc20332d4>] in walk_symlink at src/ns/chan.c:1700
#10 [<0xffffffffc20332d4>] in walk_symlink at src/ns/chan.c:1700
#11 [<0xffffffffc2032df2>] in walk at src/ns/chan.c:871
#12 [<0xffffffffc20334c9>] in __namec_from at src/ns/chan.c:1138
#13 [<0xffffffffc20340af>] in namec at src/ns/chan.c:1516
#14 [<0xffffffffc203d72d>] in sysbind at src/ns/sysfile.c:467
#15 [<0xffffffffc2055b1e>] in sys_nbind at src/syscall.c:2170
#16 [<0xffffffffc20594d9>] in syscall at src/syscall.c:2462
#17 [<0xffffffffc20596a4>] in run_local_syscall at src/syscall.c:2497
#18 [<0xffffffffc2059bd9>] in prep_syscalls at src/syscall.c:2517
#19 [<0xffffffffc20ab56a>] in sysenter_callwrapper at arch/x86/trap.c:854
kernel warning at kern/src/ns/convM2D.c:52, from core 2: nbuf 4096,
STAT_FIX_LEN_9P 49 BIT16SZ 2, GBIT16(buf) 0
Stack Backtrace on Core 2:
#01 [<0xffffffffc200a30c>] in backtrace at src/kdebug.c:220
#02 [<0xffffffffc2009ba4>] in _warn at src/init.c:323
#03 [<0xffffffffc2034cdd>] in statcheck at src/ns/convM2D.c:51
#04 [<0xffffffffc203df88>] in validstat at src/ns/sysfile.c:961
#05 [<0xffffffffc203efee>] in sysfwstat at src/ns/sysfile.c:421
#06 [<0xffffffffc2055d10>] in sys_fwstat at src/syscall.c:2271
#07 [<0xffffffffc20594d9>] in syscall at src/syscall.c:2462
#08 [<0xffffffffc20596a4>] in run_local_syscall at src/syscall.c:2497
#09 [<0xffffffffc2059bd9>] in prep_syscalls at src/syscall.c:2517
#10 [<0xffffffffc20ab56a>] in sysenter_callwrapper at arch/x86/trap.c:854


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.