netdev - Re: [PATCH] rxrpc: Fix uninitialized error code in rxrpc_send_data

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Date:   Tue, 4 Jun 2019 09:17:23 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     David Howells <dhowells@...hat.com>
Cc:     Igor Konopko <igor.j.konopko@...el.com>,
        "Mohit P . Tahiliani" <tahiliani@...k.edu.in>,
        Takashi Sakamoto <o-takashi@...amocchi.jp>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Matias Bjorling <mb@...htnvm.io>,
        Jiri Pirko <jiri@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Clemens Ladisch <clemens@...isch.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Joe Perches <joe@...ches.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        linux-block@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        linux-afs@...ts.infradead.org,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] rxrpc: Fix uninitialized error code in rxrpc_send_data_packet()

Hi David,

On Fri, May 31, 2019 at 12:35 PM David Howells <dhowells@...hat.com> wrote:
> Here's my take on the patch.
>
> David
> ---
> rxrpc: Fix uninitialized error code in rxrpc_send_data_packet()
>
> With gcc 4.1:
>
>     net/rxrpc/output.c: In function ‘rxrpc_send_data_packet’:
>     net/rxrpc/output.c:338: warning: ‘ret’ may be used uninitialized in this function
>
> Indeed, if the first jump to the send_fragmentable label is made, and
> the address family is not handled in the switch() statement, ret will be
> used uninitialized.
>
> Fix this by BUG()'ing as is done in other places in rxrpc where internal
> support for future address families will need adding.  It should not be
> possible to reach this normally as the address families are checked
> up-front.
>
> Fixes: 5a924b8951f835b5 ("rxrpc: Don't store the rxrpc header in the Tx queue sk_buffs")
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: David Howells <dhowells@...hat.com>

I'm not such a big fan of BUG(), so I'd go for ret = -EAFNOSUPPORT, but given
rxrpc is already full of BUG() calls, I guess it is an acceptable solution.

> ---
> diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
> index 004c762c2e8d..6f2b4fb4b0aa 100644
> --- a/net/rxrpc/output.c
> +++ b/net/rxrpc/output.c
> @@ -523,6 +523,9 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
>                 }
>                 break;
>  #endif
> +
> +       default:
> +               BUG();
>         }
>
>         if (ret < 0)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds