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

[Kamal Mostafa]

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-3.8.y-queue branch of the 3.8.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-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.13.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From b9b0ef8ea02978d6cebdd8ef4ab14aeacc807606 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: net: heap overflow in __audit_sockaddr()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[ Upstream commit 1661bf364ae9c506bc8795fef70d1532931be1e8 ]

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: Kamal Mostafa <kamal 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 f0a1ba6..8903258 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 a61db06..809e941 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1980,6 +1980,16 @@ 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)
@@ -1998,8 +2008,11 @@ 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;
@@ -2207,8 +2220,11 @@ 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;
--
1.8.1.2