[PATCH 4.9 011/108] ipv6: Inhibit IPv4-mapped src address on the wire.

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Jonathan T. Leighton" <jtleight@xxxxxxxx>


[ Upstream commit ec5e3b0a1d41fbda0cc33a45bc9e54e91d9d12c7 ]

This patch adds a check for the problematic case of an IPv4-mapped IPv6
source address and a destination address that is neither an IPv4-mapped
IPv6 address nor in6addr_any, and returns an appropriate error. The
check in done before returning from looking up the route.

Signed-off-by: Jonathan T. Leighton <jtleight@xxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv6/ip6_output.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1019,6 +1019,9 @@ static int ip6_dst_lookup_tail(struct ne
 		}
 	}
 #endif
+	if (ipv6_addr_v4mapped(&fl6->saddr) &&
+	    !(ipv6_addr_v4mapped(&fl6->daddr) || ipv6_addr_any(&fl6->daddr)))
+		return -EAFNOSUPPORT;
 
 	return 0;