[CIFS][PATCH] Clarify SMB1 code for delete

[Steve French <smfrench@gmail.com>]

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Coverity also complains about the way we calculate the offset
(starting from the address of a 4 byte array within the
header structure rather than from the beginning of the struct
plus 4 bytes) for SMB1 SetFileDisposition (which is used to
unlink a file by setting the delete on close flag).  This
changeset doesn't change the address but makes it slightly
clearer.

Addresses-Coverity: 711524 ("Out of bounds write")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifssmb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a513a89aad1a..0863238ddd20 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -5763,7 +5763,8 @@ CIFSSMBSetFileDisposition(const unsigned int
xid, struct cifs_tcon *tcon,
  param_offset = offsetof(struct smb_com_transaction2_sfi_req, Fid) - 4;
  offset = param_offset + params;

- data_offset = (char *) (&pSMB->hdr.Protocol) + offset;
+ /* SMB offsets are from the beginning of SMB which is 4 bytes in,
after RFC1001 field */
+ data_offset = (char *)(pSMB) + offset + 4;

  count = 1;
  pSMB->MaxParameterCount = cpu_to_le16(2);

-- 
Thanks,

Steve

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From 532db4bf85f9f2fae13154ffc45cfb71279a5dab Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Tue, 6 Jul 2021 21:42:08 -0500
Subject: [PATCH] CIFS: Clarify SMB1 code for delete

Coverity also complains about the way we calculate the offset
(starting from the address of a 4 byte array within the
header structure rather than from the beginning of the struct
plus 4 bytes) for SMB1 SetFileDisposition (which is used to
unlink a file by setting the delete on close flag).  This
changeset doesn't change the address but makes it slightly
clearer.

Addresses-Coverity: 711524 ("Out of bounds write")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifssmb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a513a89aad1a..0863238ddd20 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -5763,7 +5763,8 @@ CIFSSMBSetFileDisposition(const unsigned int xid, struct cifs_tcon *tcon,
 	param_offset = offsetof(struct smb_com_transaction2_sfi_req, Fid) - 4;
 	offset = param_offset + params;
 
-	data_offset = (char *) (&pSMB->hdr.Protocol) + offset;
+	/* SMB offsets are from the beginning of SMB which is 4 bytes in, after RFC1001 field */
+	data_offset = (char *)(pSMB) + offset + 4;
 
 	count = 1;
 	pSMB->MaxParameterCount = cpu_to_le16(2);
-- 
2.30.2