CIFS: Clarify SMB1 code for UnixSetPathInfo

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 doing SetPathInfo (setattr) when using the Unix
extensions.  This doesn't change the address but makes it
slightly clearer.

Addresses-Coverity: 711528 ("Out of bounds read")
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a14d3f5..22b8c12 100644 (file)
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -6064,9 +6064,8 @@ setPermsRetry:
        param_offset = offsetof(struct smb_com_transaction2_spi_req,
                                InformationLevel) - 4;
        offset = param_offset + params;
-       data_offset =
-           (FILE_UNIX_BASIC_INFO *) ((char *) &pSMB->hdr.Protocol +
-                                     offset);
+       /* SMB offsets are from the beginning of SMB which is 4 bytes in, after RFC1001 field */
+       data_offset = (FILE_UNIX_BASIC_INFO *)((char *) pSMB + offset + 4);
        memset(data_offset, 0, count);
        pSMB->DataOffset = cpu_to_le16(offset);
        pSMB->ParameterOffset = cpu_to_le16(param_offset);