[PATCH 4.19 56/77] ALSA: usb-audio: Fix UBSAN warnings for MIDI jacks

Greg Kroah-Hartman
2021-01-11T13:52:53Z

From: Takashi Iwai <tiwai@suse.de>

commit c06ccf3ebb7503706ea49fd248e709287ef385a3 upstream.

The calculation of in_cables and out_cables bitmaps are done with the
bit shift by the value from the descriptor, which is an arbitrary
value, and can lead to UBSAN shift-out-of-bounds warnings.

Fix it by filtering the bad descriptor values with the check of the
upper bound 0x10 (the cable bitmaps are 16 bits).

Reported-by: syzbot+92e45ae45543f89e8c88@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201223174557.10249-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/usb/midi.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1890,6 +1890,8 @@ static int snd_usbmidi_get_ms_info(struc
ms_ep = find_usb_ms_endpoint_descriptor(hostep);
if (!ms_ep)
continue;
+ if (ms_ep->bNumEmbMIDIJack > 0x10)
+ continue;
if (usb_endpoint_dir_out(ep)) {
if (endpoints[epidx].out_ep) {
if (++epidx >= MIDI_MAX_ENDPOINTS) {
@@ -2142,6 +2144,8 @@ static int snd_usbmidi_detect_roland(str
cs_desc[1] == USB_DT_CS_INTERFACE &&
cs_desc[2] == 0xf1 &&
cs_desc[3] == 0x02) {
+ if (cs_desc[4] > 0x10 || cs_desc[5] > 0x10)
+ continue;
endpoint->in_cables = (1 << cs_desc[4]) - 1;
endpoint->out_cables = (1 << cs_desc[5]) - 1;
return snd_usbmidi_detect_endpoints(umidi, endpoint, 1);