On Thu, 25 Oct 2012 17:34:38 +0400
Pavel Shilovsky <pshilovsky@xxxxxxxxx> wrote:
> 2012/10/25 Dan Carpenter <dan.carpenter@xxxxxxxxxx>:
> > Hello Pavel Shilovsky,
> >
> > This is a semi-automatic email about new static checker warnings.
> >
> > The patch f9c6e234c3ca: "CIFS: Move readpage code to ops struct" from
> > Sep 18, 2012, leads to the following Smatch complaint:
> >
> > fs/cifs/file.c:2954 cifs_read()
> > warn: variable dereferenced before check 'tcon->ses' (see line 2932)
> >
> > fs/cifs/file.c
> > 2931 tcon = tlink_tcon(open_file->tlink);
> > 2932 server = tcon->ses->server;
> > ^^^^^^^^^^^
> > New dereference.
> >
> > 2933
> > 2934 if (!server->ops->sync_read) {
> > 2935 free_xid(xid);
> > 2936 return -ENOSYS;
> > 2937 }
> > 2938
> > 2939 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
> > 2940 pid = open_file->pid;
> > 2941 else
> > 2942 pid = current->tgid;
> > 2943
> > 2944 if ((file->f_flags & O_ACCMODE) == O_WRONLY)
> > 2945 cFYI(1, "attempting read on write only file instance");
> > 2946
> > 2947 for (total_read = 0, cur_offset = read_data; read_size > total_read;
> > 2948 total_read += bytes_read, cur_offset += bytes_read) {
> > 2949 current_read_size = min_t(uint, read_size - total_read, rsize);
> > 2950 /*
> > 2951 * For windows me and 9x we do not want to request more than it
> > 2952 * negotiated since it will refuse the read then.
> > 2953 */
> > 2954 if ((tcon->ses) && !(tcon->ses->capabilities &
> > ^^^^^^^^^
> > Old check.
> >
> > 2955 tcon->ses->server->vals->cap_large_files)) {
>
> I don't think that tcon->ses can be NULL here - it seems that we can
> remove this check. Thoughts?
>
Agreed. I think that this is a holdover from some really old code
before we fixed up all the refcounting and object lifetime. The tcon
should be holding a reference to its session object, which in turn
holds a reference to the server object. If tcon->ses is NULL then
something is very, very wrong. I believe you can just remove that check.
> > 2956 current_read_size = min_t(uint, current_read_size,
> >
> > regards,
> > dan carpenter
> > --
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>
>
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
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