staging/rts5208: Fix read overflow in memcpy

BugLink: https://bugs.launchpad.net/bugs/1798539

commit 88a5b39b upstream.

Noticed by FORTIFY_SOURCE, this swaps memcpy() for strncpy() to zero-value
fill the end of the buffer instead of over-reading a string from .rodata.
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
[kees: wrote commit log]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Wayne Porter <wporter82@gmail.com>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/staging/rts5208/rtsx_scsi.c

@@ -536,7 +536,7 @@ static int inquiry(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 
 	if (sendbytes > 8) {
 		memcpy(buf, inquiry_buf, 8);
-		memcpy(buf + 8, inquiry_string,	sendbytes - 8);
+		strncpy(buf + 8, inquiry_string, sendbytes - 8);
 		if (pro_formatter_flag) {
 			/* Additional Length */
 			buf[4] = 0x33;