Umsdos bug and query

Peter Benie (
Mon, 10 Feb 97 04:51 GMT

In linux-2.0.27/fs/umsdos/namei.c, there is a bug which will be
triggered when the disk is full or has some other fault.
On line 724, result the entry for the --linux-.--- file is created. If
it fails, msdos_create can return without setting result. iput will
then be called with result set to an uninitialised value.

Line 712 /* #Specification: mkdir / umsdos directory / create EMD
When we created a new sub-directory in a UMSDOS
directory (one with full UMSDOS semantic), we
create immediately an EMD file in the new
sub-directory so it inherit UMSDOS semantic.
struct inode *subdir;
ret = umsdos_real_lookup (dir,info.fake.fname
if (ret == 0){
struct inode *result;
Line 724 ret = msdos_create (subdir,UMSDOS_EMD_FILE
subdir = NULL;
Line 726 iput (result);
if (ret < 0){
printk ("UMSDOS: Can't create empty --linux-.---\n");
iput (subdir);

It would be better if the printk were written:
printk (KERN_INFO "UMSDOS: Can't create empty " UMSDOS_EMD_FILE "\n");

On a related topic, is it possible to have an msdos directory under a
msdos directory? I've tried creating the directory under umsdos and
removing the --linux-.--- file under MSDOS. When you do this, '..' is
missing from the subdirectory causing getcwd to fail. '..' appears to
be present under MSDOS, but I wouldn't trust it to tell me the truth.

Peter Benie