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USB: serial: spcp8x5: fix modem-status handling

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commit 5ed8d41023 upstream.

Make sure to detect short control transfers and return zero on success
when retrieving the modem status.

This fixes the TIOCMGET implementation which since e1ed212d85 ("USB:
spcp8x5: add proper modem-status support") has returned TIOCM_LE on
successful retrieval, and avoids leaking bits from the stack on short
transfers.

This also fixes the carrier-detect implementation which since the above
mentioned commit unconditionally has returned true.

Fixes: e1ed212d85 ("USB: spcp8x5: add proper modem-status support")
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>
This commit is contained in:
Johan Hovold 2017-01-12 14:56:21 +01:00 committed by Greg Kroah-Hartman
parent 22034ee5da
commit 06b1cf346a
1 changed files with 7 additions and 1 deletions
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8
drivers/usb/serial/spcp8x5.c
View File

@ -232,11 +232,17 @@ static int spcp8x5_get_msr(struct usb_serial_port *port, u8 *status)
ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
GET_UART_STATUS, GET_UART_STATUS_TYPE,
0, GET_UART_STATUS_MSR, buf, 1, 100);
if (ret < 0)
if (ret < 1) {
dev_err(&port->dev, "failed to get modem status: %d\n", ret);
if (ret >= 0)
ret = -EIO;
goto out;
}
dev_dbg(&port->dev, "0xc0:0x22:0:6 %d - 0x02%x\n", ret, *buf);
*status = *buf;
ret = 0;
out:
kfree(buf);
return ret;