[PATCH 5.4.y] openvswitch: Fix unsafe attribute parsing in output_userspace()

[Eelco Chaudron <echaudro@redhat.com>]

This patch replaces the manual Netlink attribute iteration in
output_userspace() with nla_for_each_nested(), which ensures that only
well-formed attributes are processed.

Fixes: ccb1352e76cf ("net: Add Open vSwitch kernel components.")
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Ilya Maximets <i.maximets@ovn.org>
Acked-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/0bd65949df61591d9171c0dc13e42cea8941da10.1746541734.git.echaudro@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 6beb6835c1fbb3f676aebb51a5fee6b77fed9308)

---
The patch did not apply cleanly due to a previously applied style
fix that corrected indentation in the original for loop. This
patch has been adjusted accordingly to account for that change.
---
 net/openvswitch/actions.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 815a55fa7356..5af7fe6312cf 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -967,8 +967,7 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
 	upcall.cmd = OVS_PACKET_CMD_ACTION;
 	upcall.mru = OVS_CB(skb)->mru;
 
-	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
-		 a = nla_next(a, &rem)) {
+	nla_for_each_nested(a, attr, rem) {
 		switch (nla_type(a)) {
 		case OVS_USERSPACE_ATTR_USERDATA:
 			upcall.userdata = a;
-- 
2.47.1