[PATCH 4.4 20/25] USB: serial: ark3116: fix register-accessor error handling

Greg Kroah-Hartman
2017-02-24T08:38:15Z

From: Johan Hovold <johan@kernel.org>

commit 9fef37d7cf170522fb354d6d0ea6de09b9b16678 upstream.

The current implementation failed to detect short transfers, something
which could lead to bits of the uninitialised heap transfer buffer
leaking to user space.

Fixes: 149fc791a452 ("USB: ark3116: Setup some basic infrastructure for new ark3116 driver.")
Fixes: f4c1e8d597d1 ("USB: ark3116: Make existing functions 16450-aware and add close and release functions.")
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/ark3116.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- a/drivers/usb/serial/ark3116.c
+++ b/drivers/usb/serial/ark3116.c
@@ -99,10 +99,17 @@ static int ark3116_read_reg(struct usb_s
usb_rcvctrlpipe(serial->dev, 0),
0xfe, 0xc0, 0, reg,
buf, 1, ARK_TIMEOUT);
- if (result < 0)
+ if (result < 1) {
+ dev_err(&serial->interface->dev,
+ "failed to read register %u: %d\n",
+ reg, result);
+ if (result >= 0)
+ result = -EIO;
+
return result;
- else
- return buf[0];
+ }
+
+ return buf[0];
}

static inline int calc_divisor(int bps)