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

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Date:   Mon, 11 Jan 2021 14:02:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+92e45ae45543f89e8c88@...kaller.appspotmail.com,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.19 56/77] ALSA: usb-audio: Fix UBSAN warnings for MIDI jacks

From: Takashi Iwai <tiwai@...e.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@...kaller.appspotmail.com
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20201223174557.10249-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);