staging: ncpfs: memory corruption in ncp_read_kernel()

staging: ncpfs: memory corruption in ncp_read_kernel()

commit 4c41aa24baa4ed338241d05494f2c595c885af8f upstream.

If the server is malicious then *bytes_read could be larger than the
size of the "target" buffer.  It would lead to memory corruption when we
do the memcpy().

Reported-by: Dr Silvio Cesare of InfoSect <Silvio Cesare <silvio.cesare@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[carnil: backport to 4.9: Files renamed from drivers/staging/ncpfs/ncplib_kernel.c
 to fs/ncpfs/ncplib_kernel.c]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>