netdev - Re: [PATCH 5/5] [RFC] devlink: Fix uninitialized error code in devlink_fmsg_prepare

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Date:   Wed, 29 May 2019 10:04:52 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Igor Konopko <igor.j.konopko@...el.com>,
        David Howells <dhowells@...hat.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 5/5] [RFC] devlink: Fix uninitialized error code in
 devlink_fmsg_prepare_skb()

Tue, May 28, 2019 at 04:24:24PM CEST, geert@...ux-m68k.org wrote:
>With gcc 4.1:
>
>    net/core/devlink.c: In function ‘devlink_fmsg_prepare_skb’:
>    net/core/devlink.c:4325: warning: ‘err’ may be used uninitialized in this function
>
>Indeed, if the list has less than *start entries, an uninitialized error
>code will be returned.
>
>Fix this by preinitializing err to zero.
>
>Fixes: 1db64e8733f65381 ("devlink: Add devlink formatted message (fmsg) API")
>Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>---
>I don't know if this can really happen, and if this is the right fix.
>Perhaps err should be initialized to some valid error code instead?

0 is correct here.
Acked-by: Jiri Pirko <jiri@...lanox.com>

Thanks!

>---
> net/core/devlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/net/core/devlink.c b/net/core/devlink.c
>index d43bc52b8840d76b..91377e4eae9a43c1 100644
>--- a/net/core/devlink.c
>+++ b/net/core/devlink.c
>@@ -4321,8 +4321,8 @@ devlink_fmsg_prepare_skb(struct devlink_fmsg *fmsg, struct sk_buff *skb,
> {
> 	struct devlink_fmsg_item *item;
> 	struct nlattr *fmsg_nlattr;
>+	int err = 0;
> 	int i = 0;
>-	int err;
> 
> 	fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
> 	if (!fmsg_nlattr)
>-- 
>2.17.1
>