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ALSA: usb-audio: Validate MS endpoint descriptors

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commit e84749a78d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2021-05-10 17:06:59 +02:00 • committed by Greg Kroah-Hartman
commit e5ffa75afb
1 changed files with 4 additions and 0 deletions
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4
sound/usb/midi.c
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@ -1889,8 +1889,12 @@ 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) {