Re: FAILED: patch "[PATCH] cifs: integer overflow in in SMB2_ioctl()" failed to apply to 4.14-stable tree

[Sudip Mukherjee <sudipm.mukherjee@gmail.com>]

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Hi Greg,

On Sun, Sep 23, 2018 at 09:28:03PM +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

The attached backported patch will apply to 4.14-stable tree.

--
Regards
Sudip

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>From 1a302acd2676a5ee24287dcc435a61b8ff38de7e Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 10 Sep 2018 14:12:07 +0300
Subject: [PATCH] cifs: integer overflow in in SMB2_ioctl()

commit 2d204ee9d671327915260071c19350d84344e096 upstream

The "le32_to_cpu(rsp->OutputOffset) + *plen" addition can overflow and
wrap around to a smaller value which looks like it would lead to an
information leak.

Fixes: 4a72dafa19ba ("SMB2 FSCTL and IOCTL worker function")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 fs/cifs/smb2pdu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 69309538ffb8..87297323d50b 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2020,14 +2020,14 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
 	/* We check for obvious errors in the output buffer length and offset */
 	if (*plen == 0)
 		goto ioctl_exit; /* server returned no data */
-	else if (*plen > 0xFF00) {
+	else if (*plen > rsp_iov.iov_len || *plen > 0xFF00) {
 		cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", *plen);
 		*plen = 0;
 		rc = -EIO;
 		goto ioctl_exit;
 	}
 
-	if (get_rfc1002_length(rsp) < le32_to_cpu(rsp->OutputOffset) + *plen) {
+	if (get_rfc1002_length(rsp) - *plen < le32_to_cpu(rsp->OutputOffset)) {
 		cifs_dbg(VFS, "Malformed ioctl resp: len %d offset %d\n", *plen,
 			le32_to_cpu(rsp->OutputOffset));
 		*plen = 0;
-- 
2.11.0