misc: mic: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200311074916.8783-1-tiwai@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mic/host/mic_x100.c

@@ -350,10 +350,10 @@ mic_x100_load_command_line(struct mic_device *mdev, const struct firmware *fw)
 	if (!buf)
 		return -ENOMEM;
 
-	len += snprintf(buf, CMDLINE_SIZE - len,
+	len += scnprintf(buf, CMDLINE_SIZE - len,
 		" mem=%dM", boot_mem);
 	if (mdev->cosm_dev->cmdline)
-		snprintf(buf + len, CMDLINE_SIZE - len, " %s",
+		scnprintf(buf + len, CMDLINE_SIZE - len, " %s",
 			 mdev->cosm_dev->cmdline);
 	memcpy_toio(cmd_line_va, buf, strlen(buf) + 1);
 	kfree(buf);