ethtool: rss: avoid device context leak on reply-build failure

We wait with filling the reply for new RSS context creation
until after the driver ->create_rxfh_context call. The driver
needs to fill some of the defaults in the context. The failure
of rss_fill_reply() is somewhat theoretical, but doesn't take
much effort to handle it properly. Call ->remove_rxfh_context().

If the driver's remove callback fails (some implementations like sfc
can return real command errors from firmware RPCs) - skip the xa_erase
and kfree, leaving the context in the xarray. This matches how
ethnl_rss_delete_doit() behaves.

Fixes: a166ab7816c5 ("ethtool: rss: support creating contexts via Netlink")
Link: https://patch.msgid.link/20260522230647.1705600-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
index f5cf214f8f85f75b121cd331c2ac932f8be3aca9..53792f53f9229fef855aa81969f837d1307f2ca5 100644 (file)
--- a/net/ethtool/rss.c
+++ b/net/ethtool/rss.c
@@ -1106,7 +1106,7 @@ int ethnl_rss_create_doit(struct sk_buff *skb, struct genl_info *info)
        ntf_fail |= rss_fill_reply(rsp, &req.base, &data.base);
        if (WARN_ON(!hdr || ntf_fail)) {
                ret = -EMSGSIZE;
-               goto exit_unlock;
+               goto err_remove_ctx;
        }
 
        genlmsg_end(rsp, hdr);
@@ -1134,6 +1134,10 @@ exit_free_rsp:
        nlmsg_free(rsp);
        return ret;
 
+err_remove_ctx:
+       if (ops->remove_rxfh_context(dev, ctx, req.rss_context, NULL))
+               /* leave the context on failure, like ethnl_rss_delete_doit() */
+               goto exit_unlock;
 err_ctx_id_free:
        xa_erase(&dev->ethtool->rss_ctx, req.rss_context);
 err_unlock_free_ctx: