netdev - Re: [PATCH 2/5] rxrpc: Fix uninitialized error code in rxrpc_send_data

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Message-ID: <4654.1559061019@warthog.procyon.org.uk>
Date:   Tue, 28 May 2019 17:30:19 +0100
From:   David Howells <dhowells@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     dhowells@...hat.com, 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@...r.kernel.org,
        linux-afs@...ts.infradead.org, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] rxrpc: Fix uninitialized error code in rxrpc_send_data_packet()

Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

> While this is not a real false-positive, I believe it cannot cause harm
> in practice, as AF_RXRPC cannot be used with other transport families
> than IPv4 and IPv6.

Agreed.

> ---
>  net/rxrpc/output.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
> index 004c762c2e8d063c..1473d774d67100c5 100644
> --- a/net/rxrpc/output.c
> +++ b/net/rxrpc/output.c
> @@ -403,8 +403,10 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
>  
>  	/* send the packet with the don't fragment bit set if we currently
>  	 * think it's small enough */
> -	if (iov[1].iov_len >= call->peer->maxdata)
> +	if (iov[1].iov_len >= call->peer->maxdata) {
> +		ret = 0;
>  		goto send_fragmentable;
> +	}
>  
>  	down_read(&conn->params.local->defrag_sem);
>  

Simply setting 0 is wrong.  That would give the impression that the thing
worked if support for a new transport address family was added and came
through this function without full modification (say AF_INET7 becomes a
thing).

A better way to do things would be to add a default case into the
send_fragmentable switch statement that either BUG's or sets -EAFNOSUPPORT.

David