netdev-genl: Hold rcu_read_lock in napi_set

JIRA: https://issues.redhat.com/browse/RHEL-77816
Upstream Status: net.git commit ed7231f

commit ed7231f
Author: Joe Damato <jdamato@fastly.com>
Date:   Thu Nov 14 17:55:59 2024 +0000

    netdev-genl: Hold rcu_read_lock in napi_set

    Hold rcu_read_lock during netdev_nl_napi_set_doit, which calls
    napi_by_id and requires rcu_read_lock to be held.

    Closes: https://lore.kernel.org/netdev/719083c2-e277-447b-b6ea-ca3acb293a03@redhat.com/
    Fixes: 1287c1a ("netdev-genl: Support setting per-NAPI config values")
    Signed-off-by: Joe Damato <jdamato@fastly.com>
    Link: https://patch.msgid.link/20241114175600.18882-1-jdamato@fastly.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Davide Caratti <dcaratti@redhat.com>

Author: dcaratti

net/core/netdev-genl.c

@@ -335,6 +335,7 @@ int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info)
 	napi_id = nla_get_u32(info->attrs[NETDEV_A_NAPI_ID]);
 
 	rtnl_lock();
+	rcu_read_lock();
 
 	napi = napi_by_id(napi_id);
 	if (napi) {
@@ -344,6 +345,7 @@ int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info)
 		err = -ENOENT;
 	}
 
+	rcu_read_unlock();
 	rtnl_unlock();
 
 	return err;