staging: ncpfs: memory corruption in ncp_read_kernel()
authorDan Carpenter <dan.carpenter@oracle.com>
Mon, 19 Mar 2018 11:07:45 +0000 (14:07 +0300)
committerBen Hutchings <ben@decadent.org.uk>
Thu, 31 May 2018 23:30:03 +0000 (00:30 +0100)
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>
fs/ncpfs/ncplib_kernel.c

index 981a956..76c6a8e 100644 (file)
@@ -982,6 +982,10 @@ ncp_read_kernel(struct ncp_server *server, const char *file_id,
                goto out;
        }
        *bytes_read = ncp_reply_be16(server, 0);
+       if (*bytes_read > to_read) {
+               result = -EINVAL;
+               goto out;
+       }
        source = ncp_reply_data(server, 2 + (offset & 1));
 
        memcpy(target, source, *bytes_read);