diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c index aac0051a2cf6..758eb21430cd 100644 --- a/drivers/hid/usbhid/hid-core.c +++ b/drivers/hid/usbhid/hid-core.c @@ -985,6 +985,7 @@ static int usbhid_parse(struct hid_device *hid) struct usb_device *dev = interface_to_usbdev (intf); struct hid_descriptor *hdesc; struct hid_class_descriptor *hcdesc; + __u8 fixed_opt_descriptors_size; u32 quirks = 0; unsigned int rsize = 0; char *rdesc; @@ -1015,7 +1016,21 @@ static int usbhid_parse(struct hid_device *hid) (hdesc->bNumDescriptors - 1) * sizeof(*hcdesc)) { dbg_hid("hid descriptor invalid, bLen=%hhu bNum=%hhu\n", hdesc->bLength, hdesc->bNumDescriptors); - return -EINVAL; + + /* + * Some devices may expose a wrong number of descriptors compared + * to the provided length. + * However, we ignore the optional hid class descriptors entirely + * so we can safely recompute the proper field. + */ + if (hdesc->bLength >= sizeof(*hdesc)) { + fixed_opt_descriptors_size = hdesc->bLength - sizeof(*hdesc); + + hid_warn(intf, "fixing wrong optional hid class descriptors count\n"); + hdesc->bNumDescriptors = fixed_opt_descriptors_size / sizeof(*hcdesc) + 1; + } else { + return -EINVAL; + } } hid->version = le16_to_cpu(hdesc->bcdHID);