Re: rtl8xxxu 4.4.5(from f23): I get a panic adding a new device to the driver

[Jes Sorensen <Jes.Sorensen@redhat.com>]

Jes Sorensen <Jes.Sorensen@redhat.com> writes:
> Xose Vazquez Perez <xose.vazquez@gmail.com> writes:
>> Hi,
>>
>> If I do:
>> # echo "0bda 8176" > /sys/bus/usb/drivers/rtl8xxxu/new_id
>
> Hi Xose,
>
> Yes please don't do that. The rtl8xxxu driver relies on the .driver_info
> field in struct use_device_id to carry information for the different
> types of devices. If you hot add a device like above, the driver will
> fail because that field now contains a NULL pointer.
>
> I should probably add a check for it in the probe function, but it will
> simply be there to spit out a warning that it doesn't work to hot add a
> device like this.
>
> If you build it with CONFIG_RTL8XXXU_UNTESTED the 0bda:8176 should be
> included in the device list.
>
> Cheers,
> Jes

Hi Xose,

I added the following patch to my tree to avoid this.

Cheers,
Jes

commit 9202f4947aac1d60084ee79c9b5294eb42ba59dc
Author: Jes Sorensen <Jes.Sorensen@redhat.com>
Date:   Thu Mar 17 13:53:48 2016 -0400

    rtl8xxxu: Fix OOPS if user tries to add device via /sys
    
    This driver relies on driver_info in struct usb_device_id, hence
    adding a device via  /sys/bus/usb/drivers/rtl8xxxu/new_id would result
    in a NULL pointer dereference.
    
    Instead print a message and return -ENODEV
    
    Reported-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
    Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
index 8d893f4..55fc00e 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
@@ -9671,6 +9671,15 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 
 	udev = usb_get_dev(interface_to_usbdev(interface));
 
+	if (!id->driver_info) {
+		dev_warn(&udev->dev,
+			 "rtl8xxxu relies on driver_info in struct usb_device_id.\n");
+		dev_warn(&udev->dev,
+			 "Adding a device via /sys/bus/usb/drivers/rtl8xxxu/new_id is not supported!\n");
+		ret = -ENODEV;
+		goto exit;
+	}
+
 	switch (id->idVendor) {
 	case USB_VENDOR_ID_REALTEK:
 		switch(id->idProduct) {