merged
On Fri, Feb 24, 2012 at 12:12 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> On Fri, 24 Feb 2012 11:59:25 -0600
> Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx> wrote:
>
>> On Thu, Feb 23, 2012 at 8:37 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>> > The cifs code will attempt to open files on lookup under certain
>> > circumstances. What happens though if we find that the file we opened
>> > was actually a FIFO or other special file?
>> >
>> > Currently, the open filehandle just ends up being leaked leading to
>> > a dentry refcount mismatch and oops on umount. Fix this by having the
>> > code close the filehandle on the server if it turns out not to be a
>> > regular file. While we're at it, change this spaghetti if statement
>> > into a switch too.
>> >
>> > Cc: stable@xxxxxxxxxxxxxxx
>> > Reported-by: CAI Qian <caiqian@xxxxxxxxxx>
>> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>> > ---
>> > fs/cifs/dir.c | 20 ++++++++++++++++++--
>> > 1 files changed, 18 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
>> > index 63a196b..bc7e244 100644
>> > --- a/fs/cifs/dir.c
>> > +++ b/fs/cifs/dir.c
>> > @@ -584,10 +584,26 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
>> > * If either that or op not supported returned, follow
>> > * the normal lookup.
>> > */
>> > - if ((rc == 0) || (rc == -ENOENT))
>> > + switch (rc) {
>> > + case 0:
>> > + /*
>> > + * The server may allow us to open things like
>> > + * FIFOs, but the client isn't set up to deal
>> > + * with that. If it's not a regular file, just
>> > + * close it and proceed as if it were a normal
>> > + * lookup.
>> > + */
>> > + if (newInode && !S_ISREG(newInode->i_mode)) {
>> > + CIFSSMBClose(xid, pTcon, fileHandle);
>> > + break;
>> > + }
>> > + case -ENOENT:
>> > posix_open = true;
>> > - else if ((rc == -EINVAL) || (rc != -EOPNOTSUPP))
>> > + case -EOPNOTSUPP:
>> > + break;
>> > + default:
>> > pTcon->broken_posix_open = true;
>> > + }
>> > }
>> > if (!posix_open)
>> > rc = cifs_get_inode_info_unix(&newInode, full_path,
>> > --
>> > 1.7.7.6
>> >
>> > --
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>>
>> One more thing, should CIFSPOSIXDelFile should be called to match
>> CIFSPOSIXOpen or CIFSMBClose is just as good enough?
>
> I don't think so...
>
> If the FIFO was already there, then you clearly don't want to remove
> it. Note that in this case, we're not failing anything -- just getting
> rid of the open filehandle and corresponding CIFS open when we realize
> that it's not a normal file.
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
--
Thanks,
Steve
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