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-rw-r--r--sound/usb/midi.c29
1 files changed, 24 insertions, 5 deletions
diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index be5c597ed40c..047b90595d65 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1826,6 +1826,28 @@ static int snd_usbmidi_create_endpoints(struct snd_usb_midi *umidi,
return 0;
}
+static struct usb_ms_endpoint_descriptor *find_usb_ms_endpoint_descriptor(
+ struct usb_host_endpoint *hostep)
+{
+ unsigned char *extra = hostep->extra;
+ int extralen = hostep->extralen;
+
+ while (extralen > 3) {
+ struct usb_ms_endpoint_descriptor *ms_ep =
+ (struct usb_ms_endpoint_descriptor *)extra;
+
+ if (ms_ep->bLength > 3 &&
+ ms_ep->bDescriptorType == USB_DT_CS_ENDPOINT &&
+ ms_ep->bDescriptorSubtype == UAC_MS_GENERAL)
+ return ms_ep;
+ if (!extra[0])
+ break;
+ extralen -= extra[0];
+ extra += extra[0];
+ }
+ return NULL;
+}
+
/*
* Returns MIDIStreaming device capabilities.
*/
@@ -1863,11 +1885,8 @@ static int snd_usbmidi_get_ms_info(struct snd_usb_midi *umidi,
ep = get_ep_desc(hostep);
if (!usb_endpoint_xfer_bulk(ep) && !usb_endpoint_xfer_int(ep))
continue;
- ms_ep = (struct usb_ms_endpoint_descriptor *)hostep->extra;
- if (hostep->extralen < 4 ||
- ms_ep->bLength < 4 ||
- ms_ep->bDescriptorType != USB_DT_CS_ENDPOINT ||
- ms_ep->bDescriptorSubtype != UAC_MS_GENERAL)
+ ms_ep = find_usb_ms_endpoint_descriptor(hostep);
+ if (!ms_ep)
continue;
if (usb_endpoint_dir_out(ep)) {
if (endpoints[epidx].out_ep) {