[PATCH AUTOSEL 4.19 040/100] CIFS: Respect SMB2 hdr preamble size in read responses

[Sasha Levin]

From: Pavel Shilovsky <pshi...@microsoft.com>

[ Upstream commit bb1bccb60c2ebd9a6f895507d1d48d5ed773814e ]

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 <pshi...@microsoft.com>
Signed-off-by: Steve French <stfre...@microsoft.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 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 86a54b809c484..8b9471904f67e 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1521,9 +1521,10 @@ 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 f0d966da7f378..6fc16329ceb45 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3000,10 +3000,10 @@ 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",
-- 
2.20.1