[PATCH net-next] devlink: fix return of uninitialized variable err

From: Yunjian Wang <redacted>

There is a potential execution path in which variable err is
returned without being properly initialized previously. Fix
this by initializing variable err to 0.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 1db64e8733f6 ("devlink: Add devlink formatted message (fmsg) API")
Signed-off-by: Yunjian Wang <redacted>
---
 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 ee828e4b1007..470215cd60b5 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -5699,7 +5699,7 @@ devlink_fmsg_prepare_skb(struct devlink_fmsg *fmsg, struct sk_buff *skb,
 	struct devlink_fmsg_item *item;
 	struct nlattr *fmsg_nlattr;
 	int i = 0;
-	int err;
+	int err = 0;
 
 	fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
 	if (!fmsg_nlattr)

-- 
2.23.0

On Fri, 8 Jan 2021 21:21:13 +0800 wangyunjian wrote:

From: Yunjian Wang <redacted>

There is a potential execution path in which variable err is
returned without being properly initialized previously. Fix
this by initializing variable err to 0.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 1db64e8733f6 ("devlink: Add devlink formatted message (fmsg) API")
Signed-off-by: Yunjian Wang <redacted>

Fixes should generally be targeting net, not net-next.

I don't think this can trigger. 

Only devlink_nl_cmd_health_reporter_diagnose_doit() can call here, and
before it does it calls devlink_fmsg_obj_nest_start() and end(), so
there will at least be DEVLINK_ATTR_FMSG_OBJ_NEST_START to iterate over.

Please double check this analysis, and resend the patch with the commit
message updated to reflect this is not a bug fix and without the fixes
tag.

Please order variable declaration lines longest to shortest.
err should be before i.

 	fmsg_nlattr = nla_nest_start_noflag(skb, DEVLINK_ATTR_FMSG);
 	if (!fmsg_nlattr)