From: Aurelien Aptel <aaptel@suse.com>
Date: Tue, 17 Oct 2017 14:47:17 +0200
Subject: [PATCH] CIFS: do not send invalid input buffer on QUERY_INFO requests
Git-commit: 48923d2a9d4f6ca909102061a4240b9896ff8ea2
Patch-mainline: v4.14-rc7
References: bsc#1144333

query_info() doesn't use the InputBuffer field of the QUERY_INFO
request, therefore according to [MS-SMB2] it must:

a) set the InputBufferOffset to 0
b) send a zero-length InputBuffer

Doing a) is trivial but b) is a bit more tricky.

The packet is allocated according to it's StructureSize, which takes
into account an extra 1 byte buffer which we don't need
here. StructureSize fields must have constant values no matter the
actual length of the whole packet so we can't just edit that constant.

Both the NetBIOS-over-TCP message length ("rfc1002 length") L and the
iovec length L' have to be updated. Since L' is computed from L we
just update L by decrementing it by one.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/smb2pdu.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index ba3865b338d8..fa17caa56128 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2191,9 +2191,13 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
 	req->PersistentFileId = persistent_fid;
 	req->VolatileFileId = volatile_fid;
 	req->AdditionalInformation = cpu_to_le32(additional_info);
-	/* 4 for rfc1002 length field and 1 for Buffer */
-	req->InputBufferOffset =
-		cpu_to_le16(sizeof(struct smb2_query_info_req) - 1 - 4);
+
+	/*
+	 * We do not use the input buffer (do not send extra byte)
+	 */
+	req->InputBufferOffset = 0;
+	inc_rfc1001_len(req, -1);
+
 	req->OutputBufferLength = cpu_to_le32(output_len);
 
 	iov[0].iov_base = (char *)req;
-- 
2.16.4