From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 19 Mar 2018 11:07:45 +0000 (+0300)
Subject: staging: ncpfs: memory corruption in ncp_read_kernel()
X-Git-Tag: v4.1.52~369
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f67d1bdb52086230095895d6d0034953967cad78;p=thirdparty%2Fkernel%2Fstable.git

staging: ncpfs: memory corruption in ncp_read_kernel()

[ Upstream commit 4c41aa24baa4ed338241d05494f2c595c885af8f ]

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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---

diff --git a/fs/ncpfs/ncplib_kernel.c b/fs/ncpfs/ncplib_kernel.c
index 88dbbc9fcf4d6..f571570a2e72c 100644
--- a/fs/ncpfs/ncplib_kernel.c
+++ b/fs/ncpfs/ncplib_kernel.c
@@ -980,6 +980,10 @@ 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);