Re: [PATCH v1 net-next 1/7] neighbour: Make neigh_valid_get_req() return ndmsg.

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: Simon Horman <horms@kernel.org>
Date: Thu, 17 Apr 2025 13:53:10 +0100
> On Tue, Apr 15, 2025 at 05:41:24PM -0700, Kuniyuki Iwashima wrote:
> > neigh_get() passes 4 local variable pointers to neigh_valid_get_req().
> > 
> > If it returns a pointer of struct ndmsg, we do not need to pass two
> > of them.
> > 
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> 
> ...
> 
> > @@ -2893,17 +2892,19 @@ static int neigh_valid_get_req(const struct nlmsghdr *nlh,
> >  		case NDA_DST:
> >  			if (nla_len(tb[i]) != (int)(*tbl)->key_len) {
> >  				NL_SET_ERR_MSG(extack, "Invalid network address in neighbor get request");
> > -				return -EINVAL;
> 
> Hi Iwashima-san,
> 
> I think you need the following here:
> 
> 				err = -EINVAL;
> 
> > +				goto err;
> >  			}
> >  			*dst = nla_data(tb[i]);
> >  			break;
> >  		default:
> >  			NL_SET_ERR_MSG(extack, "Unsupported attribute in neighbor get request");
> > -			return -EINVAL;
> 
> And here.
> 
> Flagged by Smatch as:
> 
>   .../neighbour.c:2907 neigh_valid_get_req() warn: passing zero to 'ERR_PTR'
> 
> > +			goto err;

Thanks for catching!

I missed nlmsg_parse_deprecated_strict() reset err to 0.

I'll explicitly set err before goto in every path instead of
initialising it first.