[PATCH] staging: wlan-ng: fix out of bounds read in prism2sta_probe_usb()

From: Rustam Kovhaev
Date: Tue Aug 04 2020 - 10:56:45 EST


let's use usb_find_common_endpoints() to discover endpoints, it does all
necessary checks for type and xfer direction

remove memset() in hfa384x_create(), because we now assign endpoints in
prism2sta_probe_usb() and because create_wlan() uses kzalloc() to
allocate hfa384x struct before calling hfa384x_create()

Fixes: faaff9765664 ("staging: wlan-ng: properly check endpoint types")
Reported-and-tested-by: syzbot+22794221ab96b0bab53a@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://syzkaller.appspot.com/bug?extid=22794221ab96b0bab53a
Signed-off-by: Rustam Kovhaev <rkovhaev@xxxxxxxxx>
---
drivers/staging/wlan-ng/hfa384x_usb.c | 5 -----
drivers/staging/wlan-ng/prism2usb.c | 19 ++++++-------------
2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/wlan-ng/hfa384x_usb.c b/drivers/staging/wlan-ng/hfa384x_usb.c
index fa1bf8b069fd..2720f7319a3d 100644
--- a/drivers/staging/wlan-ng/hfa384x_usb.c
+++ b/drivers/staging/wlan-ng/hfa384x_usb.c
@@ -524,13 +524,8 @@ static void hfa384x_usb_defer(struct work_struct *data)
*/
void hfa384x_create(struct hfa384x *hw, struct usb_device *usb)
{
- memset(hw, 0, sizeof(*hw));
hw->usb = usb;

- /* set up the endpoints */
- hw->endp_in = usb_rcvbulkpipe(usb, 1);
- hw->endp_out = usb_sndbulkpipe(usb, 2);
-
/* Set up the waitq */
init_waitqueue_head(&hw->cmdq);

diff --git a/drivers/staging/wlan-ng/prism2usb.c b/drivers/staging/wlan-ng/prism2usb.c
index 456603fd26c0..4b08dc1da4f9 100644
--- a/drivers/staging/wlan-ng/prism2usb.c
+++ b/drivers/staging/wlan-ng/prism2usb.c
@@ -61,23 +61,14 @@ static int prism2sta_probe_usb(struct usb_interface *interface,
const struct usb_device_id *id)
{
struct usb_device *dev;
- const struct usb_endpoint_descriptor *epd;
- const struct usb_host_interface *iface_desc = interface->cur_altsetting;
+ struct usb_endpoint_descriptor *bulk_in, *bulk_out;
+ struct usb_host_interface *iface_desc = interface->cur_altsetting;
struct wlandevice *wlandev = NULL;
struct hfa384x *hw = NULL;
int result = 0;

- if (iface_desc->desc.bNumEndpoints != 2) {
- result = -ENODEV;
- goto failed;
- }
-
- result = -EINVAL;
- epd = &iface_desc->endpoint[1].desc;
- if (!usb_endpoint_is_bulk_in(epd))
- goto failed;
- epd = &iface_desc->endpoint[2].desc;
- if (!usb_endpoint_is_bulk_out(epd))
+ result = usb_find_common_endpoints(iface_desc, &bulk_in, &bulk_out, NULL, NULL);
+ if (result)
goto failed;

dev = interface_to_usbdev(interface);
@@ -96,6 +87,8 @@ static int prism2sta_probe_usb(struct usb_interface *interface,
}

/* Initialize the hw data */
+ hw->endp_in = usb_rcvbulkpipe(dev, bulk_in->bEndpointAddress);
+ hw->endp_out = usb_sndbulkpipe(dev, bulk_out->bEndpointAddress);
hfa384x_create(hw, dev);
hw->wlandev = wlandev;

--
2.27.0