Commit 34cf6eed authored Dec 23, 2020 by Takashi Iwai Committed by Greg Kroah-Hartman Jan 12, 2021

ALSA: usb-audio: Fix UBSAN warnings for MIDI jacks



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>

parent dbe90bed

sound/usb/midi.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1865,6 +1865,8 @@ static int snd_usbmidi_get_ms_info(struct snd_usb_midi *umidi,
		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) {
		@@ -2117,6 +2119,8 @@ static int snd_usbmidi_detect_roland(struct snd_usb_midi *umidi,
		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);