From: Pavel Shilovsky <pshilov@microsoft.com>
Date: Thu, 17 Jan 2019 16:18:38 -0800
Subject: [PATCH] CIFS: Respect SMB2 hdr preamble size in read responses
Git-commit: bb1bccb60c2ebd9a6f895507d1d48d5ed773814e
Patch-mainline: v5.1-rc1
References: bsc#1144333

There are a couple places where we still account for 4 bytes
in the beginning of SMB2 packet which is not true in the current
code. Fix this to use a header preamble size where possible.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifssmb.c | 7 ++++---
 fs/cifs/smb2ops.c | 6 +++---
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 683c7c9d5a02..3f4e40abaad4 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1612,9 +1612,10 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 
 	/* set up first two iov for signature check and to get credits */
 	rdata->iov[0].iov_base = buf;
-	rdata->iov[0].iov_len = 4;
-	rdata->iov[1].iov_base = buf + 4;
-	rdata->iov[1].iov_len = server->total_read - 4;
+	rdata->iov[0].iov_len = server->vals->header_preamble_size;
+	rdata->iov[1].iov_base = buf + server->vals->header_preamble_size;
+	rdata->iov[1].iov_len =
+		server->total_read - server->vals->header_preamble_size;
 	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
 		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
 	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 5adfe68f4754..7291d8289511 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3244,10 +3244,10 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 
 	/* set up first two iov to get credits */
 	rdata->iov[0].iov_base = buf;
-	rdata->iov[0].iov_len = 4;
-	rdata->iov[1].iov_base = buf + 4;
+	rdata->iov[0].iov_len = 0;
+	rdata->iov[1].iov_base = buf;
 	rdata->iov[1].iov_len =
-		min_t(unsigned int, buf_len, server->vals->read_rsp_size) - 4;
+		min_t(unsigned int, buf_len, server->vals->read_rsp_size);
 	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
 		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
 	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
-- 
2.16.4