[PATCH 3/3 V2] usb: usbtmc: Fix erroneous generic_read ioctl return

[Dave Penkler <dpenkler@gmail.com>]

wait_event_interruptible_timeout returns a long
The return value was being assigned to an int causing an integer overflow
when the remaining jiffies > INT_MAX which resulted in random error
returns.

Use a long return value, converting to the int ioctl return only on error.

Fixes: bb99794a4792 ("usb: usbtmc: Add ioctl for vendor specific read")
Cc: stable@vger.kernel.org
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
---
Change V1 -> V2
  Acc cc to stable line

 drivers/usb/class/usbtmc.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index b3ca89b0dab7..025a7aa795e3 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -833,6 +833,7 @@ static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
 	unsigned long expire;
 	int bufcount = 1;
 	int again = 0;
+	long wait_rv;
 
 	/* mutex already locked */
 
@@ -945,19 +946,24 @@ static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
 		if (!(flags & USBTMC_FLAG_ASYNC)) {
 			dev_dbg(dev, "%s: before wait time %lu\n",
 				__func__, expire);
-			retval = wait_event_interruptible_timeout(
+			wait_rv = wait_event_interruptible_timeout(
 				file_data->wait_bulk_in,
 				usbtmc_do_transfer(file_data),
 				expire);
 
-			dev_dbg(dev, "%s: wait returned %d\n",
-				__func__, retval);
+			dev_dbg(dev, "%s: wait returned %ld\n",
+				__func__, wait_rv);
+
+			if (wait_rv < 0) {
+				retval = wait_rv;
+				goto error;
+			}
 
-			if (retval <= 0) {
-				if (retval == 0)
-					retval = -ETIMEDOUT;
+			if (wait_rv == 0) {
+				retval = -ETIMEDOUT;
 				goto error;
 			}
+
 		}
 
 		urb = usb_get_from_anchor(&file_data->in_anchor);
-- 
2.49.0