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Date:   Wed, 26 Jan 2022 22:59:37 +0100
From:   Pavel Machek <pavel@denx.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Antony Antony <antony.antony@secunet.com>,
        Eyal Birger <eyal.birger@gmail.com>,
        Steffen Klassert <steffen.klassert@secunet.com>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 5.10 173/563] xfrm: interface with if_id 0 should return
 error
Message-ID: <20220126215937.GA31158@duo.ucw.cz>
References: <20220124184024.407936072@linuxfoundation.org>
 <20220124184030.397155595@linuxfoundation.org>
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Hi!

> [ Upstream commit 8dce43919566f06e865f7e8949f5c10d8c2493f5 ]
>=20
> xfrm interface if_id =3D 0 would cause xfrm policy lookup errors since
> Commit 9f8550e4bd9d.
>=20
> Now explicitly fail to create an xfrm interface when if_id =3D 0

This will break changelink completely, AFAICT.

> @@ -672,7 +677,12 @@ static int xfrmi_changelink(struct net_device *dev, =
struct nlattr *tb[],
>  {
>  	struct xfrm_if *xi =3D netdev_priv(dev);
>  	struct net *net =3D xi->net;
> -	struct xfrm_if_parms p;
> +	struct xfrm_if_parms p =3D {};
> +
> +	if (!p.if_id) {
> +		NL_SET_ERR_MSG(extack, "if_id must be non zero");
> +		return -EINVAL;
> +	}
> =20
>  	xfrmi_netlink_parms(data, &p);
>  	xi =3D xfrmi_locate(net, &p);

if_id will be always 0, because it was not yet initialized.

Best regards,
									Pavel

Signed-off-by: Pavel Machek <pavel@denx.de>

diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 57448fc519fc..eb028b835f70 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -673,12 +673,11 @@ static int xfrmi_changelink(struct net_device *dev, s=
truct nlattr *tb[],
 	struct net *net =3D xi->net;
 	struct xfrm_if_parms p =3D {};
=20
+	xfrmi_netlink_parms(data, &p);
 	if (!p.if_id) {
 		NL_SET_ERR_MSG(extack, "if_id must be non zero");
 		return -EINVAL;
 	}
-
-	xfrmi_netlink_parms(data, &p);
 	xi =3D xfrmi_locate(net, &p);
 	if (!xi) {
 		xi =3D netdev_priv(dev);


--=20
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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