[PATCH 4.9 27/45] USB: serial: iuu_phoenix: fix DMA from stack

Greg Kroah-Hartman
2021-01-11T14:07:59Z

From: Johan Hovold <johan@kernel.org>

commit 54d0a3ab80f49f19ee916def62fe067596833403 upstream.

Stack-allocated buffers cannot be used for DMA (on all architectures) so
allocate the flush command buffer using kmalloc().

Fixes: 60a8fc017103 ("USB: add iuu_phoenix driver")
Cc: stable <stable@vger.kernel.org> # 2.6.25
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/serial/iuu_phoenix.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/usb/serial/iuu_phoenix.c
+++ b/drivers/usb/serial/iuu_phoenix.c
@@ -553,23 +553,29 @@ static int iuu_uart_flush(struct usb_ser
struct device *dev = &port->dev;
int i;
int status;
- u8 rxcmd = IUU_UART_RX;
+ u8 *rxcmd;
struct iuu_private *priv = usb_get_serial_port_data(port);

if (iuu_led(port, 0xF000, 0, 0, 0xFF) < 0)
return -EIO;

+ rxcmd = kmalloc(1, GFP_KERNEL);
+ if (!rxcmd)
+ return -ENOMEM;
+
+ rxcmd[0] = IUU_UART_RX;
+
for (i = 0; i < 2; i++) {
- status = bulk_immediate(port, &rxcmd, 1);
+ status = bulk_immediate(port, rxcmd, 1);
if (status != IUU_OPERATION_OK) {
dev_dbg(dev, "%s - uart_flush_write error\n", __func__);
- return status;
+ goto out_free;
}

status = read_immediate(port, &priv->len, 1);
if (status != IUU_OPERATION_OK) {
dev_dbg(dev, "%s - uart_flush_read error\n", __func__);
- return status;
+ goto out_free;
}

if (priv->len > 0) {
@@ -577,12 +583,16 @@ static int iuu_uart_flush(struct usb_ser
status = read_immediate(port, priv->buf, priv->len);
if (status != IUU_OPERATION_OK) {
dev_dbg(dev, "%s - uart_flush_read error\n", __func__);
- return status;
+ goto out_free;
}
}
}
dev_dbg(dev, "%s - uart_flush_read OK!\n", __func__);
iuu_led(port, 0, 0xF000, 0, 0xFF);
+
+out_free:
+ kfree(rxcmd);
+
return status;
}