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. > > > Is it possible to explicit the magic number 6 and 3 in the code. Currently, > it looks like it comes from no where. 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'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 -- 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
