From e84749a78dc82bc545f12ce009e3dbcc2c5a8a91 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 10 May 2021 17:06:59 +0200
Subject: [PATCH] ALSA: usb-audio: Validate MS endpoint descriptors
Git-commit: e84749a78dc82bc545f12ce009e3dbcc2c5a8a91
Patch-mainline: v5.13-rc3
References: git-fixes
snd_usbmidi_get_ms_info() may access beyond the border when a
malformed descriptor is passed. This patch adds the sanity checks of
the given MS endpoint descriptors, and skips invalid ones.
Reported-by: syzbot+6bb23a5d5548b93c94aa@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210510150659.17710-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/midi.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index a10ac75969a8..649eb8d1ab7d 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1956,8 +1956,12 @@ 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->bLength <= sizeof(*ms_ep))
+ continue;
if (ms_ep->bNumEmbMIDIJack > 0x10)
continue;
+ if (ms_ep->bLength < sizeof(*ms_ep) + ms_ep->bNumEmbMIDIJack)
+ continue;
if (usb_endpoint_dir_out(ep)) {
if (endpoints[epidx].out_ep) {
if (++epidx >= MIDI_MAX_ENDPOINTS) {
--
2.26.2