From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: [patch] net: heap overflow in __audit_sockaddr()
Date: Wed, 2 Oct 2013 21:58:11 +0300
Message-ID: <20131002185811.GA23438@elgon.mountain>
References: <20130319.095547.1333124517060824574.davem@davemloft.net>
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Cc: netdev@vger.kernel.org, security@kernel.org,
	=?iso-8859-1?Q?J=FCri?= Aedla <juri.aedla@gmail.com>
To: "David S. Miller" <davem@davemloft.net>
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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 t=
o
exploit this bug.

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

Reported-by: J=FCri Aedla <juri.aedla@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/net/socket.c b/net/socket.c
index ebed4b6..c226ace 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1964,6 +1964,16 @@ struct used_address {
 	unsigned int name_len;
 };
=20
+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 *m=
sg,
 			 struct msghdr *msg_sys, unsigned int flags,
 			 struct used_address *used_address)
@@ -1982,8 +1992,11 @@ static int ___sys_sendmsg(struct socket *sock, s=
truct 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 =3D copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}
=20
 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err =3D -EMSGSIZE;
@@ -2191,8 +2204,11 @@ static int ___sys_recvmsg(struct socket *sock, s=
truct 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 =3D copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}
=20
 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err =3D -EMSGSIZE;