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

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Date:   Tue, 28 May 2019 16:24:24 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     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>
Cc:     linux-block@...r.kernel.org, netdev@...r.kernel.org,
        linux-afs@...ts.infradead.org, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH 5/5] [RFC] devlink: Fix uninitialized error code in devlink_fmsg_prepare_skb()

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?
---
 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