Commit c06ccf3e authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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



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: default avatar <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: default avatarTakashi Iwai <tiwai@suse.de>
parent c1e89523

sound/usb/midi.c

+4 −0
Original line number Diff line number Diff line
@@ -1889,6 +1889,8 @@ 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) {
@@ -2141,6 +2143,8 @@ 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);