Re: [PATCH 3/3] virtiofsd: Check file type in lo_flush()

[Dr. David Alan Gilbert]

* Vivek Goyal (vgoyal@redhat.com) wrote:
> On Thu, Dec 10, 2020 at 08:03:03PM +0000, Dr. David Alan Gilbert wrote:
> > * Vivek Goyal (vgoyal@redhat.com) wrote:
> > > Currently lo_flush() is written in such a way that it expects to receive
> > > a FLUSH requests on a regular file (and not directories). For example,
> > > we call lo_fi_fd() which searches lo->fd_map. If we open directories
> > > using opendir(), we keep don't keep track of these in lo->fd_map instead
> > > we keep them in lo->dir_map. So we expect lo_flush() to be called on
> > > regular files only.
> > > 
> > > Even linux fuse client calls FLUSH only for regular files and not
> > > directories. So put a check for filetype and return EBADF if
> > > lo_flush() is called on a non-regular file.
> > > 
> > > Reported-by: Laszlo Ersek <lersek@redhat.com>
> > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> > > ---
> > >  tools/virtiofsd/passthrough_ll.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/virtiofsd/passthrough_ll.c 
> > > b/tools/virtiofsd/passthrough_ll.c
> > > index 8ba79f503a..48a109d3f6 100644
> > > --- a/tools/virtiofsd/passthrough_ll.c
> > > +++ b/tools/virtiofsd/passthrough_ll.c
> > > @@ -1968,7 +1968,7 @@ static void lo_flush(fuse_req_t req, fuse_ino_t 
> > > ino, struct fuse_file_info *fi)
> > >      struct lo_data *lo = lo_data(req);
> > >  
> > >      inode = lo_inode(req, ino);
> > > -    if (!inode) {
> > > +    if (!inode || !S_ISREG(inode->filetype)) {
> > >          fuse_reply_err(req, EBADF);
> > 
> > Does that need a lo_inode_put(lo, &inode) in the new case?
> 
> Good catch. Yes if inode is valid but file type is not regular, we need
> to put inode reference.
> 
> Do you want me to post a new patch or you will like to take care of
> it.

OK, so if we make this :

  if (!inode) {
      fuse_reply_err(req, EBADF);
      return;
  }

  if (!S_ISREG(inode->filetype)) {
      lo_inode_put(lo_data(req), &inode);
      fuse_reply_err(req, EBADF);
      return;
  }

(Untested)

Dave

> 
> Vivek
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK