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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, David Ahern <dsahern@kernel.org>,
        Vadim Fedorenko <vfedorenko@novek.ru>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.10 094/125] net: ipv6: fix return value of ip6_skb_dst_mtu
Date:   Thu, 22 Jul 2021 18:31:25 +0200
Message-Id: <20210722155627.813308798@linuxfoundation.org>
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From: Vadim Fedorenko <vfedorenko@novek.ru>

commit 40fc3054b45820c28ea3c65e2c86d041dc244a8a upstream.

Commit 628a5c561890 ("[INET]: Add IP(V6)_PMTUDISC_RPOBE") introduced
ip6_skb_dst_mtu with return value of signed int which is inconsistent
with actually returned values. Also 2 users of this function actually
assign its value to unsigned int variable and only __xfrm6_output
assigns result of this function to signed variable but actually uses
as unsigned in further comparisons and calls. Change this function
to return unsigned int value.

Fixes: 628a5c561890 ("[INET]: Add IP(V6)_PMTUDISC_RPOBE")
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/net/ip6_route.h |    2 +-
 net/ipv6/xfrm6_output.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -262,7 +262,7 @@ static inline bool ipv6_anycast_destinat
 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		 int (*output)(struct net *, struct sock *, struct sk_buff *));
 
-static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
+static inline unsigned int ip6_skb_dst_mtu(struct sk_buff *skb)
 {
 	int mtu;
 
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -56,7 +56,7 @@ static int __xfrm6_output(struct net *ne
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct xfrm_state *x = dst->xfrm;
-	int mtu;
+	unsigned int mtu;
 	bool toobig;
 
 #ifdef CONFIG_NETFILTER