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From: Xin Long <lucien.xin@gmail.com>
Date: Sun, 14 May 2023 15:52:29 -0400
Subject: [PATCH] tipc: check the bearer min mtu properly when setting it by
 netlink
References: bsc#1012628
Patch-mainline: 6.3.4
Git-commit: 35a089b5d793d2bfd2cc7cfa6104545184de2ce7

[ Upstream commit 35a089b5d793d2bfd2cc7cfa6104545184de2ce7 ]

Checking the bearer min mtu with tipc_udp_mtu_bad() only works for
IPv4 UDP bearer, and IPv6 UDP bearer has a different value for the
min mtu. This patch checks with encap_hlen + TIPC_MIN_BEARER_MTU
for min mtu, which works for both IPv4 and IPv6 UDP bearer.

Note that tipc_udp_mtu_bad() is still used to check media min mtu
in __tipc_nl_media_set(), as m->mtu currently is only used by the
IPv4 UDP bearer as its default mtu value.

Fixes: 682cd3cf946b ("tipc: confgiure and apply UDP bearer MTU on running links")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/tipc/bearer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 0e9a29e1..53881406 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -1151,8 +1151,8 @@ int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
 				return -EINVAL;
 			}
 #ifdef CONFIG_TIPC_MEDIA_UDP
-			if (tipc_udp_mtu_bad(nla_get_u32
-					     (props[TIPC_NLA_PROP_MTU]))) {
+			if (nla_get_u32(props[TIPC_NLA_PROP_MTU]) <
+			    b->encap_hlen + TIPC_MIN_BEARER_MTU) {
 				NL_SET_ERR_MSG(info->extack,
 					       "MTU value is out-of-range");
 				return -EINVAL;
-- 
2.35.3