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")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 22b8c12962fa93804fbc7ea3d23ee940b3ff6509..a513a89aad1a7017ac8d581168706d9ed24c4dd6 100644 (file)
--- 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;