segfaults and kernel oops with long filenames

[Willi Langenberger]

Hi arla drinkers!

We encountered the following arla behaviour (tested with versions 0.32
- 0.34.4 on redhat/i386 6.0 - 6.2) while working with a somewhat buggy
htdig. A "stat" call to a non existant filename with more than 255
charcters gives a segfault and a kernel oops. 255 characters work as
expected:

  byron:~$ perl -le 'stat("/afs/wu-wien.ac.at/tmp/" . "a"x255) || print $!'
  No such file or directory

But:

  byron:~$ perl -le 'stat("/afs/wu-wien.ac.at/tmp/" . "a"x256) || print $!'
  Segmentation fault

And the syslog says:

  Oct 17 18:10:34 byron kernel: invalid operand: 0000 
  Oct 17 18:10:34 byron kernel: CPU:    0 
  Oct 17 18:10:34 byron kernel: EIP:    0010:[real_lookup+60/160] 
  Oct 17 18:10:34 byron kernel: EFLAGS: 00010282 
  Oct 17 18:10:34 byron kernel: eax: 00000000   ebx: fffffff4   ecx: d68cf0e4   edx: e08553f9 
  Oct 17 18:10:34 byron kernel: esi: d691a140   edi: d6991650   ebp: d699169c   esp: d6a77f58 
  Oct 17 18:10:34 byron kernel: ds: 0018   es: 0018   ss: 0018 
  Oct 17 18:10:34 byron kernel: Process perl (pid: 621, process nr: 44, stackpage=d6a77000) 
  Oct 17 18:10:34 byron kernel: Stack: d6a77f88 00000000 d68b410c 00000001 c012cf10 d6a52e60 d6a77f88 00000001  
  Oct 17 18:10:34 byron kernel:        d68b4000 d68b4000 080e6f48 bffffaf0 d68b400c 00000100 00000000 c012cff8  
  Oct 17 18:10:34 byron kernel:        d68b4000 d6a52e60 00000001 d6a76000 080c9ee0 c012b05e 080e6f48 00000001  
  Oct 17 18:10:34 byron kernel: Call Trace: [lookup_dentry+296/488] [__namei+40/88] [sys_newstat+14/96] [system_call+52/56]  
  Oct 17 18:10:34 byron kernel: Code: ff ff 83 c4 08 85 f6 74 21 8b 47 64 56 57 8b 40 08 ff d0 89  

After that, the afs module seems to behave unpredictable: eg, each
process accessing the "/afs/wu-wien.ac.at/tmp" volume (with a valid
filename) hangs in a "disk wait". But i don't know, how to reproduce
this...

If i can help with further investigation, please let me know!


\wlang{}

-- 
Willi.Langenberger at wu-wien.ac.at                 Fax: +43/1/31336/702
Zentrum fuer Informatikdienste, Wirtschaftsuniversitaet Wien, Austria