net: ethtool: Don't call .cleanup_data when prepare_data fails

There's a consistent pattern where the .cleanup_data() callback is
called when .prepare_data() fails, when it should really be called to
clean after a successful .prepare_data() as per the documentation.

Rewrite the error-handling paths to make sure we don't cleanup
un-prepared data.

Fixes: c781ff12a2f3 ("ethtool: Allow network drivers to dump arbitrary EEPROM data")
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20250407130511.75621-1-maxime.chevallier@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index a163d40c6431b9b623e702f2318d26dc457fa458..977beeaaa2f991c17c03116dcd15e46fad7288eb 100644 (file)
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -500,7 +500,7 @@ static int ethnl_default_doit(struct sk_buff *skb, struct genl_info *info)
                netdev_unlock_ops(req_info->dev);
        rtnl_unlock();
        if (ret < 0)
-               goto err_cleanup;
+               goto err_dev;
        ret = ops->reply_size(req_info, reply_data);
        if (ret < 0)
                goto err_cleanup;
@@ -560,7 +560,7 @@ static int ethnl_default_dump_one(struct sk_buff *skb, struct net_device *dev,
        netdev_unlock_ops(dev);
        rtnl_unlock();
        if (ret < 0)
-               goto out;
+               goto out_cancel;
        ret = ethnl_fill_reply_header(skb, dev, ctx->ops->hdr_attr);
        if (ret < 0)
                goto out;
@@ -569,6 +569,7 @@ static int ethnl_default_dump_one(struct sk_buff *skb, struct net_device *dev,
 out:
        if (ctx->ops->cleanup_data)
                ctx->ops->cleanup_data(ctx->reply_data);
+out_cancel:
        ctx->reply_data->dev = NULL;
        if (ret < 0)
                genlmsg_cancel(skb, ehdr);
@@ -793,7 +794,7 @@ static void ethnl_default_notify(struct net_device *dev, unsigned int cmd,
        ethnl_init_reply_data(reply_data, ops, dev);
        ret = ops->prepare_data(req_info, reply_data, &info);
        if (ret < 0)
-               goto err_cleanup;
+               goto err_rep;
        ret = ops->reply_size(req_info, reply_data);
        if (ret < 0)
                goto err_cleanup;
@@ -828,6 +829,7 @@ err_skb:
 err_cleanup:
        if (ops->cleanup_data)
                ops->cleanup_data(reply_data);
+err_rep:
        kfree(reply_data);
        kfree(req_info);
        return;