net: heap overflow in __audit_sockaddr()

[ 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@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[wt: 2.6.32: msg_sys is a struct, not a pointer]
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/compat.c b/net/compat.c
index 9559afc639c138a52d0d9ce8d49b83c7ce8abfaa..da3d0fce433a733ead1fcf3e015fdd8580cf72a4 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -69,6 +69,8 @@ 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 bf9fc68a554cf6b884cae123364cbecfb9655672..9f8cd744f0b02954d34c65e043a03cc822309f26 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1863,6 +1863,16 @@ SYSCALL_DEFINE2(shutdown, int, fd, int, how)
 #define COMPAT_NAMELEN(msg)    COMPAT_MSG(msg, msg_namelen)
 #define COMPAT_FLAGS(msg)      COMPAT_MSG(msg, msg_flags)
 
+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;
+}
+
 /*
  *     BSD sendmsg interface
  */
@@ -1887,8 +1897,11 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct msghdr __user *, msg, unsigned, 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;
+       }
 
        sock = sockfd_lookup_light(fd, &err, &fput_needed);
        if (!sock)
@@ -1997,8 +2010,11 @@ SYSCALL_DEFINE3(recvmsg, int, fd, struct msghdr __user *, msg,
                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;
+       }
 
        sock = sockfd_lookup_light(fd, &err, &fput_needed);
        if (!sock)