From: Steve French <stfrench@microsoft.com>
Date: Thu, 1 Jul 2021 17:46:23 -0500
Subject: [PATCH] cifs: clarify SMB1 code for UnixCreateHardLink
Git-commit: 819f916c835d0d022117ad97cb3a658546352ab8
References: bsc#1190317
Patch-mainline: v5.14-rc1

Coverity 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).  This doesn't change the address but
makes it slightly clearer.

Addresses-Coverity: 711529 ("Out of bounds read")
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/cifspdu.h | 1 +
 fs/cifs/cifssmb.c | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 0923f72d27e9..f6e235001358 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -1785,6 +1785,7 @@ struct smb_com_transaction2_sfi_req {
 	__u16 Fid;
 	__le16 InformationLevel;
 	__u16 Reserved4;
+	__u8  payload[];
 } __attribute__((packed));
 
 struct smb_com_transaction2_sfi_rsp {
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 58ebec4d4413..ea12fa6eacb6 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -3009,7 +3009,8 @@ CIFSUnixCreateHardLink(const unsigned int xid, struct cifs_tcon *tcon,
 				InformationLevel) - 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;
 	if (pSMB->hdr.Flags2 & SMBFLG2_UNICODE) {
 		name_len_target =
 		    cifsConvertToUTF16((__le16 *) data_offset, fromName,
-- 
2.33.0