diff options
| -rw-r--r-- | lib/libusb/libusb20_desc.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/lib/libusb/libusb20_desc.c b/lib/libusb/libusb20_desc.c index 517a2e5972c3..3052af09e9c2 100644 --- a/lib/libusb/libusb20_desc.c +++ b/lib/libusb/libusb20_desc.c @@ -81,9 +81,10 @@ libusb20_parse_config_desc(const void *config_desc) if (ptr[1] != LIBUSB20_DT_CONFIG) { return (NULL); /* not config descriptor */ } + /* - * The first "bInterfaceNumber" should never have the value 0xff. - * Then it is corrupt. + * The first "bInterfaceNumber" cannot start at 0xFFFF + * because the field is 8-bit. */ niface_no_alt = 0; nendpoint = 0; @@ -206,12 +207,15 @@ libusb20_parse_config_desc(const void *config_desc) if (libusb20_me_decode(ptr, ptr[0], &last_if->desc)) { /* ignore */ } - /* - * Sometimes USB devices have corrupt interface - * descriptors and we need to overwrite the provided - * interface number! - */ - last_if->desc.bInterfaceNumber = niface - 1; + + /* detect broken USB descriptors when USB debugging is enabled */ + if (last_if->desc.bInterfaceNumber != (uint8_t)(niface - 1)) { + const char *str = getenv("LIBUSB_DEBUG"); + if (str != NULL && str[0] != '\0' && str[0] != '0') { + printf("LIBUSB_DEBUG: bInterfaceNumber(%u) is not sequential(%u)\n", + last_if->desc.bInterfaceNumber, niface - 1); + } + } last_if->extra.ptr = LIBUSB20_ADD_BYTES(ptr, ptr[0]); last_if->extra.len = 0; last_if->extra.type = LIBUSB20_ME_IS_RAW; |