reproducible panic with mount_smbfs

[Attilio Rao]

2008/11/2, Attilio Rao <attilio at freebsd.org>:
> 2008/11/2, Yuri Pankov <yuri.pankov at gmail.com>:
>
> > Hi,
>  >
>  >  Trying to mount nonexistent smb share with mount_smbfs leads to
>  >  following panic:
>  >
>  >  # mount_smbfs //yuri at lifebane/blahblah /mnt
>  >
>  >  Unread portion of the kernel message buffer:
>  >  smb_co_lock: recursive lock for object 1
>  >  panic: Lock (lockmgr) smb_vc not locked @
>  >  /usr/src/sys/modules/smbfs/../../netsmb/smb_conn.c:329.
>  >  cpuid = 0
>  >  KDB: stack backtrace:
>  >  db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
>  >  panic() at panic+0x182
>  >  witness_assert() at witness_assert+0x21a
>  >  __lockmgr_args() at __lockmgr_args+0x17a
>  >  smb_co_put() at smb_co_put+0x76
>  >  smb_sm_lookup() at smb_sm_lookup+0xfe
>  >  smb_usr_lookup() at smb_usr_lookup+0xcd
>  >  nsmb_dev_ioctl() at nsmb_dev_ioctl+0x1f6
>  >  giant_ioctl() at giant_ioctl+0x75
>  >  devfs_ioctl_f() at devfs_ioctl_f+0x76
>  >  kern_ioctl() at kern_ioctl+0x92
>  >  ioctl() at ioctl+0xfd
>  >  syscall() at syscall+0x1bf
>  >  Xfast_syscall() at Xfast_syscall+0xab
>  >  --- syscall (54, FreeBSD ELF64, ioctl), rip = 0x800939aec, rsp =
>  >  0x7fffffffe038, rbp = 0x7fffffffe450 ---
>  >  Uptime: 6m46s
>  >  Physical memory: 2032 MB
>
>
> So, what is happening here is that smb_co_lock() is AFU.
>  Infact looking at the code:
>  int
>  smb_co_lock(struct smb_connobj *cp, int flags, struct thread *td)
>  {
>  ...
>         if (smb_co_lockstatus(cp, td) == LK_EXCLUSIVE &&
>             (flags & LK_CANRECURSE) == 0) {
>                 SMBERROR("recursive lock for object %d\n", cp->co_level);
>                 return 0;
>         }
>  ...

Yuri,
could you please test this fix:
http://www.freebsd.org/~attilio/netsmb.diff

and report if it works?
You could get a KASSERT running but this is expected as I want to
identify on the callers who passes a malformed request and fix it.

Thanks,
Attilio


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