[PATCH 3.18 01/20] ip: zero sockaddr returned on error queue

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Willem de Bruijn <willemb@google.com>

[ Upstream commit f812116b174e59a350acc8e4856213a166a91222 ]

The sockaddr is returned in IP(V6)_RECVERR as part of errhdr. That
structure is defined and allocated on the stack as

    struct {
            struct sock_extended_err ee;
            struct sockaddr_in(6)    offender;
    } errhdr;

The second part is only initialized for certain SO_EE_ORIGIN values.
Always initialize it completely.

An MTU exceeded error on a SOCK_RAW/IPPROTO_RAW is one example that
would return uninitialized bytes.

Signed-off-by: Willem de Bruijn <willemb@google.com>

----

Also verified that there is no padding between errhdr.ee and
errhdr.offender that could leak additional kernel data.
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/ip_sockglue.c |    8 ++------
 net/ipv6/datagram.c    |   10 +++-------
 2 files changed, 5 insertions(+), 13 deletions(-)

--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -443,15 +443,11 @@ int ip_recv_error(struct sock *sk, struc
 
 	memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
 	sin = &errhdr.offender;
-	sin->sin_family = AF_UNSPEC;
+	memset(sin, 0, sizeof(*sin));
 	if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP) {
-		struct inet_sock *inet = inet_sk(sk);
-
 		sin->sin_family = AF_INET;
 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
-		sin->sin_port = 0;
-		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
-		if (inet->cmsg_flags)
+		if (inet_sk(sk)->cmsg_flags)
 			ip_cmsg_recv(msg, skb);
 	}
 
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -383,11 +383,10 @@ int ipv6_recv_error(struct sock *sk, str
 
 	memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
 	sin = &errhdr.offender;
-	sin->sin6_family = AF_UNSPEC;
+	memset(sin, 0, sizeof(*sin));
+
 	if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {
 		sin->sin6_family = AF_INET6;
-		sin->sin6_flowinfo = 0;
-		sin->sin6_port = 0;
 		if (np->rxopt.all)
 			ip6_datagram_recv_common_ctl(sk, msg, skb);
 		if (skb->protocol == htons(ETH_P_IPV6)) {
@@ -398,12 +397,9 @@ int ipv6_recv_error(struct sock *sk, str
 				ipv6_iface_scope_id(&sin->sin6_addr,
 						    IP6CB(skb)->iif);
 		} else {
-			struct inet_sock *inet = inet_sk(sk);
-
 			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
 					       &sin->sin6_addr);
-			sin->sin6_scope_id = 0;
-			if (inet->cmsg_flags)
+			if (inet_sk(sk)->cmsg_flags)
 				ip_cmsg_recv(msg, skb);
 		}
 	}