[PATCH 5.12 245/296] net: hso: check for allocation failure in hso_create_bulk_serial_device()

Greg Kroah-Hartman
2021-05-31T16:53:30Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 31db0dbd72444abe645d90c20ecb84d668f5af5e ]

In current kernels, small allocations never actually fail so this
patch shouldn't affect runtime.

Originally this error handling code written with the idea that if
the "serial->tiocmget" allocation failed, then we would continue
operating instead of bailing out early. But in later years we added
an unchecked dereference on the next line.

serial->tiocmget->serial_state_notification = kzalloc();
^^^^^^^^^^^^^^^^^^

Since these allocations are never going fail in real life, this is
mostly a philosophical debate, but I think bailing out early is the
correct behavior that the user would want. And generally it's safer to
bail as soon an error happens.

Fixes: af0de1303c4e ("usb: hso: obey DMA rules in tiocmget")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/usb/hso.c | 37 ++++++++++++++++++-------------------
1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index ba366e9347f7..b947b7a9ffb8 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2618,29 +2618,28 @@ static struct hso_device *hso_create_bulk_serial_device(
num_urbs = 2;
serial->tiocmget = kzalloc(sizeof(struct hso_tiocmget),
GFP_KERNEL);
+ if (!serial->tiocmget)
+ goto exit;
serial->tiocmget->serial_state_notification
= kzalloc(sizeof(struct hso_serial_state_notification),
GFP_KERNEL);
- /* it isn't going to break our heart if serial->tiocmget
- * allocation fails don't bother checking this.
- */
- if (serial->tiocmget && serial->tiocmget->serial_state_notification) {
- tiocmget = serial->tiocmget;
- tiocmget->endp = hso_get_ep(interface,
- USB_ENDPOINT_XFER_INT,
- USB_DIR_IN);
- if (!tiocmget->endp) {
- dev_err(&interface->dev, "Failed to find INT IN ep\n");
- goto exit;
- }
-
- tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
- if (tiocmget->urb) {
- mutex_init(&tiocmget->mutex);
- init_waitqueue_head(&tiocmget->waitq);
- } else
- hso_free_tiomget(serial);
+ if (!serial->tiocmget->serial_state_notification)
+ goto exit;
+ tiocmget = serial->tiocmget;
+ tiocmget->endp = hso_get_ep(interface,
+ USB_ENDPOINT_XFER_INT,
+ USB_DIR_IN);
+ if (!tiocmget->endp) {
+ dev_err(&interface->dev, "Failed to find INT IN ep\n");
+ goto exit;
}
+
+ tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (tiocmget->urb) {
+ mutex_init(&tiocmget->mutex);
+ init_waitqueue_head(&tiocmget->waitq);
+ } else
+ hso_free_tiomget(serial);
}
else
num_urbs = 1;
--
2.30.2