Re: [PATCH 5.10 173/563] xfrm: interface with if_id 0 should return error

[Pavel Machek]

Hi!

> [ Upstream commit 8dce43919566f06e865f7e8949f5c10d8c2493f5 ]
> 
> xfrm interface if_id = 0 would cause xfrm policy lookup errors since
> Commit 9f8550e4bd9d.
> 
> Now explicitly fail to create an xfrm interface when if_id = 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 = netdev_priv(dev);
>  	struct net *net = xi->net;
> -	struct xfrm_if_parms p;
> +	struct xfrm_if_parms p = {};
> +
> +	if (!p.if_id) {
> +		NL_SET_ERR_MSG(extack, "if_id must be non zero");
> +		return -EINVAL;
> +	}
>  
>  	xfrmi_netlink_parms(data, &p);
>  	xi = 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@xxxxxxx>

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, struct nlattr *tb[],
 	struct net *net = xi->net;
 	struct xfrm_if_parms p = {};
 
+	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 = xfrmi_locate(net, &p);
 	if (!xi) {
 		xi = netdev_priv(dev);


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