2017-09-27 23:29 GMT+09:00 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Wed, 27 Sep 2017, Michel Hermier wrote: > >> Le 27 sept. 2017 07:42, "Alan Stern" <stern@xxxxxxxxxxxxxxxxxxx> a écrit : > >> > - for (n = 0; n < hdesc->bNumDescriptors; n++) >> > + num_descriptors = min_t(int, hdesc->bNumDescriptors, >> > + (hdesc->bLength - 6) / 3); >> > + for (n = 0; n < num_descriptors; n++) >> > if (hdesc->desc[n].bDescriptorType == HID_DT_REPORT) >> > rsize = le16_to_cpu(hdesc->desc[n]. >> wDescriptorLength); >> >> Yes, this is a lot better. OK. >> >> >> Is it possible to explicit the magic number 6 and 3 in the code. Currently, >> it looks like it comes from no where. I gree with you. > > Yes, it is possible. The 6 is equal to > > offsetof(struct hid_descriptor, desc) > > and the 3 is equal to > > sizeof(struct hid_class_descriptor) > > (at least, I think it is -- the structure is marked as packed so its > size should be 3). > > In this case I found the numbers to be more readable, but other people > may have different opinions. I will post V2 shortly. > >> I'm also wondering if this change will not affect some devices in the wild, >> by rejecting hid descriptors with num descriptors == 0 ? > > It's possible, but I doubt it. If such devices do exist, they should > never have worked in the first place. Certainly they would generate > warnings or errors during enumeration because of their invalid > descriptors. > > Alan Stern > Jaejoong -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
