Re: [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32

Pavel Skripkin
2021-08-24T07:01:26Z

On 8/24/21 9:58 AM, Dan Carpenter wrote:
> On Sun, Aug 22, 2021 at 05:36:01PM +0300, Pavel Skripkin wrote:
>> -static u32 usb_read32(struct intf_hdl *pintfhdl, u32 addr)
>> +static int usb_read32(struct intf_hdl *pintfhdl, u32 addr, u32 *data)
>> {
>> u8 requesttype;
>> u16 wvalue;
>> u16 len;
>> - __le32 data;
>> + int res;
>> + __le32 tmp;
>> +
>> + if (WARN_ON(unlikely(!data)))
>> + return -EINVAL;
>>
>> requesttype = 0x01;/* read_in */
>>
>> wvalue = (u16)(addr & 0x0000ffff);
>> len = 4;
>>
>> - usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype);
>> + res = usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype);
>> + if (res < 0) {
>> + dev_err(dvobj_to_dev(pintfhdl->pintf_dev), "Failed to read 32 bytes: %d\n", res);
>
> Add a return here. Try to keep the success path and the failure path
> as separate as possible. Try to keep the success path indented at one
> tab so the code looks like this:
>
> success();
> success();
> if (fail)
> handle_failure();
> success();
> success();
>
> Try to deal with exceptions as quickly as possible so that the reader
> has less to remember.
>
>> + } else {
>> + /* Noone cares about positive return value */
>
> Ugh... That's unfortunate. We should actually care. The
> usbctrl_vendorreq() has an information leak where it copies len (4)
> bytes of data even if usb_control_msg() is not able to read len bytes.
>
> The best fix would be to remove the information leak and make
> usbctrl_vendorreq() return zero on success. In other words something
> like:
>
> status = usb_control_msg();
> if (status < 0)
> return status;
> if (status != len)
> return -EIO;
> status = 0;
>

I see, thank you for reviewing, will fix in v3! I fully forgot, that
usb_control_msg() can receive only part of the message :)

With regards,
Pavel Skripkin