Hi! > commit e7b931bee739e8a77ae216e613d3b99342b6dec0 upstream. > > The driver would happily overwrite its write buffer with user data in > 256 byte increments due to a removed buffer-space sanity check.
> +++ b/drivers/usb/serial/iuu_phoenix.c
> @@ -697,14 +697,16 @@ static int iuu_uart_write(struct tty_str
> struct iuu_private *priv = usb_get_serial_port_data(port);
> unsigned long flags;
>
> - if (count > 256)
> - return -ENOMEM;
> -
> spin_lock_irqsave(&priv->lock, flags);
>
> + count = min(count, 256 - priv->writelen);
> + if (count == 0)
> + goto out;
> +
> /* fill the buffer */
> memcpy(priv->writebuf + priv->writelen, buf, count);
> priv->writelen += count;
> +out:
> spin_unlock_irqrestore(&priv->lock, flags);
>
> return count;
Ok, so... goto and label is unneccessary, memcpy will do the right
thing with count == 0.
But what is worse, this changes return value in the error case;
returning 0 instead of -ENOMEM. I don't believe 0 is appropriate
return code here.
(It should block on the write buffer if blocking or return -EAGAIN if
nonblocking, right?)
Best regards,
Pavel
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