[PATCH[[CIFS] Clarify SMB1 code for POSIX delete file

[PATCH[[CIFS] Clarify SMB1 code for POSIX delete file

[Steve French]

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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 CIFSPOSIXDelFile. This changeset
    doesn't change the address but makes it slightly clearer.

    Addresses-Coverity: 711519 ("Out of bounds write")
    Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index d4144c182604..65d1a65bfc37 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -873,8 +873,11 @@ CIFSPOSIXDelFile(const unsigned int xid, struct
cifs_tcon *tcon,
                                InformationLevel) - 4;
        offset = param_offset + params;

-       /* Setup pointer to Request Data (inode type) */
-       pRqD = (struct unlink_psx_rq *)(((char *)&pSMB->hdr.Protocol) + offset);
+       /* Setup pointer to Request Data (inode type).
+        * Note that SMB offsets are from the beginning of SMB which is 4 bytes
+        * in, after RFC1001 field
+        */
+       pRqD = (struct unlink_psx_rq *)((char *)(pSMB) + offset + 4);
        pRqD->type = cpu_to_le16(type);
        pSMB->ParameterOffset = cpu_to_le16(param_offset);
        pSMB->DataOffset = cpu_to_le16(offset);


-- 
Thanks,

Steve

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From 7b09d4e0be94968b7c6c117e34ca90cea9c6d986 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Thu, 22 Jul 2021 14:35:15 -0500
Subject: [PATCH] CIFS: Clarify SMB1 code for POSIX delete file

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 CIFSPOSIXDelFile. This changeset
doesn't change the address but makes it slightly clearer.

Addresses-Coverity: 711519 ("Out of bounds write")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifssmb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index d4144c182604..65d1a65bfc37 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -873,8 +873,11 @@ CIFSPOSIXDelFile(const unsigned int xid, struct cifs_tcon *tcon,
 				InformationLevel) - 4;
 	offset = param_offset + params;
 
-	/* Setup pointer to Request Data (inode type) */
-	pRqD = (struct unlink_psx_rq *)(((char *)&pSMB->hdr.Protocol) + offset);
+	/* Setup pointer to Request Data (inode type).
+	 * Note that SMB offsets are from the beginning of SMB which is 4 bytes
+	 * in, after RFC1001 field
+	 */
+	pRqD = (struct unlink_psx_rq *)((char *)(pSMB) + offset + 4);
 	pRqD->type = cpu_to_le16(type);
 	pSMB->ParameterOffset = cpu_to_le16(param_offset);
 	pSMB->DataOffset = cpu_to_le16(offset);
-- 
2.30.2