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Subject[PATCH 3.12 076/122] ip: zero sockaddr returned on error queue
Date
From: Willem de Bruijn <willemb@google.com>

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

===============

[ 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: Jiri Slaby <jslaby@suse.cz>
---
net/ipv4/ip_sockglue.c | 8 ++------
net/ipv6/datagram.c | 10 +++-------
2 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 23e6ab0a2dc0..f6603142cb33 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -410,15 +410,11 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)

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);
}

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index c66c6df6e881..9f9ad99fcfdd 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -374,11 +374,10 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)

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 (skb->protocol == htons(ETH_P_IPV6)) {
sin->sin6_addr = ipv6_hdr(skb)->saddr;
if (np->rxopt.all)
@@ -387,12 +386,9 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
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);
}
}
--
2.2.2


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