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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Code looks correct.
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
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