linux-kernel - Re: [PATCH/RFC] RDMA/iwpm: Fix uninitialized error code in iwpm_send

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Date:   Thu, 16 Nov 2017 13:21:22 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Tatyana Nikolova <Tatyana.E.Nikolova@...el.com>,
        Roland Dreier <roland@...estorage.com>,
        Doug Ledford <dledford@...hat.com>,
        linux-rdma <linux-rdma@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH/RFC] RDMA/iwpm: Fix uninitialized error code in
 iwpm_send_mapinfo()

On Thu, Nov 16, 2017 at 11:50:48AM +0100, Arnd Bergmann wrote:
> On Thu, Nov 16, 2017 at 11:26 AM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
> > With gcc-4.1.2:
> >
> >     drivers/infiniband/core/iwpm_util.c: In function ‘iwpm_send_mapinfo’:
> >     drivers/infiniband/core/iwpm_util.c:647: warning: ‘ret’ may be used uninitialized in this function
> >
> > Indeed, if nl_client is not found in any of the scanned has buckets, ret
> > will be used uninitialized.
> >
> > Preinitialize ret to zero to fix this.
> >
> > Fixes: 30dc5e63d6a5ad24 ("RDMA/core: Add support for iWARP Port Mapper user space service")
> > Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> > ---
> > RFC as I have no idea if this can ever happen, and if yes, what's the
> > correct behavior to handle it:
> >   - return 0,
> >   - return an error code,
> >   - don't send anything,
> >   - anything else?
>
> This looks like a reasonable warning. I don't see on my box with any compiler
> version. Do you have a configuration I can use to reproduce it, I'd just like
> to see out of curiosity which other compilers report it.
>
> Looking at one caller (iwpm_mapping_info_cb), it seems that we try to make
> sure that nl_client is valid first by calling iwpm_valid_client(), and returning
> -EINVAL otherwise, so that seems like an appropriate return code if any
> caller forgets to test for iwpm_valid_client() first.

The checks of nl_client are leftovers from RDMA core netlink refactoring
work. The call to iwpm_mapping_info_cb() can occur only if core checked
and identified this client as safe.

Thanks

>
>       Arnd
> --
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