[PATCH][CIFS] Clarify code for SMB1 SetFileSize

[PATCH][CIFS] Clarify code for SMB1 SetFileSize

[Steve French]

[-- Attachment #1: Type: text/plain, Size: 1255 bytes --]

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 setting the file size using SMB1. This changeset
doesn't change the address but makes it slightly clearer.

Addresses-Coverity: 711525 ("Out of bounds write")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifssmb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 22b8c12962fa..a513a89aad1a 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -5628,9 +5628,9 @@ CIFSSMBSetFileSize(const unsigned int xid,
struct cifs_tcon *tcon,
  pSMB->TotalDataCount = pSMB->DataCount;
  pSMB->TotalParameterCount = pSMB->ParameterCount;
  pSMB->ParameterOffset = cpu_to_le16(param_offset);
+ /* SMB offsets are from the beginning of SMB which is 4 bytes in,
after RFC1001 field */
  parm_data =
- (struct file_end_of_file_info *) (((char *) &pSMB->hdr.Protocol)
- + offset);
+ (struct file_end_of_file_info *)(((char *)pSMB) + offset + 4);
  pSMB->DataOffset = cpu_to_le16(offset);
  parm_data->FileSize = cpu_to_le64(size);
  pSMB->Fid = cfile->fid.netfid;

-- 
Thanks,

Steve

[-- Attachment #2: 0001-CIFS-Clarify-SMB1-code-for-SetFileSize.patch --]
[-- Type: text/x-patch, Size: 1462 bytes --]

From 1194128e37edf86c7e2bbb61f878573f54fb0e80 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Tue, 6 Jul 2021 21:27:26 -0500
Subject: [PATCH] CIFS: Clarify SMB1 code for SetFileSize

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 setting the file size using SMB1. This changeset
doesn't change the address but makes it slightly clearer.

Addresses-Coverity: 711525 ("Out of bounds write")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifssmb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 22b8c12962fa..a513a89aad1a 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -5628,9 +5628,9 @@ CIFSSMBSetFileSize(const unsigned int xid, struct cifs_tcon *tcon,
 	pSMB->TotalDataCount = pSMB->DataCount;
 	pSMB->TotalParameterCount = pSMB->ParameterCount;
 	pSMB->ParameterOffset = cpu_to_le16(param_offset);
+	/* SMB offsets are from the beginning of SMB which is 4 bytes in, after RFC1001 field */
 	parm_data =
-		(struct file_end_of_file_info *) (((char *) &pSMB->hdr.Protocol)
-				+ offset);
+		(struct file_end_of_file_info *)(((char *)pSMB) + offset + 4);
 	pSMB->DataOffset = cpu_to_le16(offset);
 	parm_data->FileSize = cpu_to_le64(size);
 	pSMB->Fid = cfile->fid.netfid;
-- 
2.30.2

Re: [PATCH][CIFS] Clarify code for SMB1 SetFileSize

[Paulo Alcantara]

Steve French <smfrench@gmail.com> writes:

> 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 setting the file size using SMB1. This changeset
> doesn't change the address but makes it slightly clearer.
>
> Addresses-Coverity: 711525 ("Out of bounds write")
> Signed-off-by: Steve French <stfrench@microsoft.com>
> ---
>  fs/cifs/cifssmb.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>