[3.5.y.z extended stable] Patch "net: heap overflow in __audit_sockaddr()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    net: heap overflow in __audit_sockaddr()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2fc6cea8f51e1352717c97fba1d261a866d6e112 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter at oracle.com>
Date: Thu, 3 Oct 2013 00:27:20 +0300
Subject: [PATCH] net: heap overflow in __audit_sockaddr()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit 1661bf364ae9c506bc8795fef70d1532931be1e8 upstream.

We need to cap ->msg_namelen or it leads to a buffer overflow when we
to the memcpy() in __audit_sockaddr().  It requires CAP_AUDIT_CONTROL to
exploit this bug.

The call tree is:
___sys_recvmsg()
  move_addr_to_user()
    audit_sockaddr()
      __audit_sockaddr()

Reported-by: Jüri Aedla <juri.aedla at gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/compat.c |  2 ++
 net/socket.c | 24 ++++++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/net/compat.c b/net/compat.c
index 9c816e8..707f5ba 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -71,6 +71,8 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
 	    __get_user(kmsg->msg_controllen, &umsg->msg_controllen) ||
 	    __get_user(kmsg->msg_flags, &umsg->msg_flags))
 		return -EFAULT;
+	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+		return -EINVAL;
 	kmsg->msg_name = compat_ptr(tmp1);
 	kmsg->msg_iov = compat_ptr(tmp2);
 	kmsg->msg_control = compat_ptr(tmp3);
diff --git a/net/socket.c b/net/socket.c
index cd51a03..c9b6b90 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1898,6 +1898,16 @@ struct used_address {
 	unsigned int name_len;
 };

+static int copy_msghdr_from_user(struct msghdr *kmsg,
+				 struct msghdr __user *umsg)
+{
+	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
+		return -EFAULT;
+	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+		return -EINVAL;
+	return 0;
+}
+
 static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
 			 struct msghdr *msg_sys, unsigned int flags,
 			 struct used_address *used_address)
@@ -1916,8 +1926,11 @@ static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
 	if (MSG_CMSG_COMPAT & flags) {
 		if (get_compat_msghdr(msg_sys, msg_compat))
 			return -EFAULT;
-	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-		return -EFAULT;
+	} else {
+		err = copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}

 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err = -EMSGSIZE;
@@ -2125,8 +2138,11 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
 	if (MSG_CMSG_COMPAT & flags) {
 		if (get_compat_msghdr(msg_sys, msg_compat))
 			return -EFAULT;
-	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-		return -EFAULT;
+	} else {
+		err = copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}

 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err = -EMSGSIZE;
--
1.8.3.2