inet: prevent leakage of uninitialized memory to user in recv syscalls

[ Upstream commit bceaa90240b6019ed73b49965eac7d167610be69 ]

Only update *addr_len when we actually fill in sockaddr, otherwise we
can return uninitialized memory from the stack to the caller in the
recvfrom, recvmmsg and recvmsg syscalls. Drop the the (addr_len == NULL)
checks because we only get called with a valid addr_len pointer either
from sock_common_recvmsg or inet_recvmsg.

If a blocking read waits on a socket which is concurrently shut down we
now return zero and set msg_msgnamelen to 0.

Reported-by: mpb <mpb.mail@gmail.com>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[wt: no ieee802154, ping nor l2tp in 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>

5 files changed, 8 insertions, 21 deletions

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 07ab583bddb3..c50344b5fda4 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -681,9 +681,6 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	if (flags & MSG_OOB)
 		goto out;
 
-	if (addr_len)
-		*addr_len = sizeof(*sin);
-
 	if (flags & MSG_ERRQUEUE) {
 		err = ip_recv_error(sk, msg, len);
 		goto out;
@@ -711,6 +708,7 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
 		sin->sin_port = 0;
 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
+		*addr_len = sizeof(*sin);
 	}
 	if (inet->cmsg_flags)
 		ip_cmsg_recv(msg, skb);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index af559e0373dc..80487ee8c488 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -941,12 +941,6 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	int err;
 	int is_udplite = IS_UDPLITE(sk);
 
-	/*
-	 *	Check any passed addresses
-	 */
-	if (addr_len)
-		*addr_len = sizeof(*sin);
-
 	if (flags & MSG_ERRQUEUE)
 		return ip_recv_error(sk, msg, len);
 
@@ -1001,6 +995,7 @@ try_again:
 		sin->sin_port = udp_hdr(skb)->source;
 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
 		memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+		*addr_len = sizeof(*sin);
 	}
 	if (inet->cmsg_flags)
 		ip_cmsg_recv(msg, skb);
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 4f24570b0869..df75f9475eb4 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -456,9 +456,6 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
 	if (flags & MSG_OOB)
 		return -EOPNOTSUPP;
 
-	if (addr_len)
-		*addr_len=sizeof(*sin6);
-
 	if (flags & MSG_ERRQUEUE)
 		return ipv6_recv_error(sk, msg, len);
 
@@ -495,6 +492,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
 		sin6->sin6_scope_id = 0;
 		if (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 			sin6->sin6_scope_id = IP6CB(skb)->iif;
+		*addr_len = sizeof(*sin6);
 	}
 
 	sock_recv_timestamp(msg, sk, skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index d8c037440078..ce291af0f95d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -200,9 +200,6 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
 	int is_udplite = IS_UDPLITE(sk);
 	int is_udp4;
 
-	if (addr_len)
-		*addr_len=sizeof(struct sockaddr_in6);
-
 	if (flags & MSG_ERRQUEUE)
 		return ipv6_recv_error(sk, msg, len);
 
@@ -273,7 +270,7 @@ try_again:
 			if (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
 				sin6->sin6_scope_id = IP6CB(skb)->iif;
 		}
-
+		*addr_len = sizeof(*sin6);
 	}
 	if (is_udp4) {
 		if (inet->cmsg_flags)
diff --git a/net/phonet/datagram.c b/net/phonet/datagram.c
index ef5c75c372e4..c88da7378c6a 100644
--- a/net/phonet/datagram.c
+++ b/net/phonet/datagram.c
@@ -122,9 +122,6 @@ static int pn_recvmsg(struct kiocb *iocb, struct sock *sk,
 	if (flags & MSG_OOB)
 		goto out_nofree;
 
-	if (addr_len)
-		*addr_len = sizeof(sa);
-
 	skb = skb_recv_datagram(sk, flags, noblock, &rval);
 	if (skb == NULL)
 		goto out_nofree;
@@ -145,8 +142,10 @@ static int pn_recvmsg(struct kiocb *iocb, struct sock *sk,
 
 	rval = (flags & MSG_TRUNC) ? skb->len : copylen;
 
-	if (msg->msg_name != NULL)
-		memcpy(msg->msg_name, &sa, sizeof(struct sockaddr_pn));
+	if (msg->msg_name != NULL) {
+		memcpy(msg->msg_name, &sa, sizeof(sa));
+		*addr_len = sizeof(sa);
+	}
 
 out:
 	skb_free_datagram(sk, skb);