Re: [bug report] IB/uverbs: clean up INIT_UDATA_BUF_OR_NULL usage

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On Mon, 2017-10-02 at 13:00 +0200, Arnd Bergmann wrote:
> On Mon, Oct 2, 2017 at 12:13 PM, Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
> > Hello Arnd Bergmann,
> > 
> > The patch 12f727721eee: "IB/uverbs: clean up INIT_UDATA_BUF_OR_NULL
> > usage" from Sep 6, 2017, leads to the following static checker
> > warning:
> > 
> >         drivers/infiniband/core/uverbs_std_types.c:249 create_udata()
> >         error: uninitialized symbol 'inbuf'.
> > 
> > drivers/infiniband/core/uverbs_std_types.c
> >    222  static void create_udata(struct uverbs_attr_bundle *ctx,
> >    223                           struct ib_udata *udata)
> >    224  {
> >    225          /*
> >    226           * This is for ease of conversion. The purpose is to convert all drivers
> >    227           * to use uverbs_attr_bundle instead of ib_udata.
> >    228           * Assume attr == 0 is input and attr == 1 is output.
> >    229           */
> >    230          void __user *inbuf;
> >    231          size_t inbuf_len = 0;
> >    232          void __user *outbuf;
> >    233          size_t outbuf_len = 0;
> >    234          const struct uverbs_attr *uhw_in =
> >    235                  uverbs_attr_get(ctx, UVERBS_UHW_IN);
> >    236          const struct uverbs_attr *uhw_out =
> >    237                  uverbs_attr_get(ctx, UVERBS_UHW_OUT);
> >    238
> >    239          if (!IS_ERR(uhw_in)) {
> >    240                  inbuf = uhw_in->ptr_attr.ptr;
> >    241                  inbuf_len = uhw_in->ptr_attr.len;
> >    242          }
> >    243
> >    244          if (!IS_ERR(uhw_out)) {
> >    245                  outbuf = uhw_out->ptr_attr.ptr;
> >    246                  outbuf_len = uhw_out->ptr_attr.len;
> >    247          }
> >    248
> >    249          ib_uverbs_init_udata_buf_or_null(udata, inbuf, outbuf, inbuf_len,
> >    250                                           outbuf_len);
> > 
> > In the original code, this was a macro so smatch understood that we
> > don't use inbuf and outbuf if they aren't initialized.  Now it's a
> > function and smatch generates a warning if you pass uninitialized
> > variables to a function.
> > 
> > It's not a bug, but it's really ugly.
> 
> I see. Should we maybe open-code the ib_uverbs_init_udata_buf_or_null()
> call in this function?
> 
> diff --git a/drivers/infiniband/core/uverbs_std_types.c
> b/drivers/infiniband/core/uverbs_std_types.c
> index b095bce7f238..039802ae7332 100644
> --- a/drivers/infiniband/core/uverbs_std_types.c
> +++ b/drivers/infiniband/core/uverbs_std_types.c
> @@ -227,27 +227,26 @@ static void create_udata(struct uverbs_attr_bundle *ctx,
>          * to use uverbs_attr_bundle instead of ib_udata.
>          * Assume attr == 0 is input and attr == 1 is output.
>          */
> -       void __user *inbuf;
> -       size_t inbuf_len = 0;
> -       void __user *outbuf;
> -       size_t outbuf_len = 0;
>         const struct uverbs_attr *uhw_in =
>                 uverbs_attr_get(ctx, UVERBS_UHW_IN);
>         const struct uverbs_attr *uhw_out =
>                 uverbs_attr_get(ctx, UVERBS_UHW_OUT);
> 
>         if (!IS_ERR(uhw_in)) {
> -               inbuf = uhw_in->ptr_attr.ptr;
> -               inbuf_len = uhw_in->ptr_attr.len;
> +               udata->inbuf = uhw_in->ptr_attr.ptr;
> +               udata->inbuf_len = uhw_in->ptr_attr.len;
> +       } else {
> +               udata->inbuf = NULL;
> +               udata->inbuf_len = 0;
>         }
> 
>         if (!IS_ERR(uhw_out)) {
> -               outbuf = uhw_out->ptr_attr.ptr;
> -               outbuf_len = uhw_out->ptr_attr.len;
> +               udata->outbuf = uhw_out->ptr_attr.ptr;
> +               udata->outbuf_len = uhw_out->ptr_attr.len;
> +       } else {
> +               udata->outbuf = NULL;
> +               udata->outbuf_len = 0;
>         }
> -
> -       ib_uverbs_init_udata_buf_or_null(udata, inbuf, outbuf, inbuf_len,
> -                                        outbuf_len);
>  }
> 
>  static int uverbs_create_cq_handler(struct ib_device *ib_dev,
> 
>        Arnd
> --
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Arnd, can you send this as a proper patch with attribution and a Signed-
off-by: please.

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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