ipv6: fix endianness error in icmpv6_err

BugLink: https://bugs.launchpad.net/bugs/1826212

[ Upstream commit dcb94b88 ]

IPv6 ping socket error handler doesn't correctly convert the new 32 bit
mtu to host endianness before using.

Cc: Lorenzo Colitti <lorenzo@google.com>
Fixes: 6d0bfe22 ("net: ipv6: Add IPv6 support to the ping socket.")
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/ipv6/icmp.c

@@ -98,7 +98,7 @@ static void icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 
 	if (!(type & ICMPV6_INFOMSG_MASK))
 		if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST)
-			ping_err(skb, offset, info);
+			ping_err(skb, offset, ntohl(info));
 }
 
 static int icmpv6_rcv(struct sk_buff *skb);