From: Johan Hovold Date: Thu, 12 Jan 2017 13:56:21 +0000 (+0100) Subject: USB: serial: spcp8x5: fix modem-status handling X-Git-Tag: firefly_0821_release~176^2~1^2^2~9 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=06b1cf346a4daa011de99ab6080ab45b396d8c01;p=firefly-linux-kernel-4.4.55.git USB: serial: spcp8x5: fix modem-status handling commit 5ed8d41023751bdd3546f2fe4118304357efe8d2 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 e1ed212d8593 ("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: e1ed212d8593 ("USB: spcp8x5: add proper modem-status support") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/serial/spcp8x5.c b/drivers/usb/serial/spcp8x5.c index 475e6c31b266..ddfd787c461c 100644 --- a/drivers/usb/serial/spcp8x5.c +++ b/drivers/usb/serial/spcp8x5.c @@ -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;