The recently introduced MIDI endpoint parser code has an access to the field without the size validation, hence it might lead to out-of-bounce access. Add the sanity checks for the descriptor sizes.

Fixes: eb596e0fd13c ("ALSA: usb-audio: generate midi streaming substream names from jack names") Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/midi.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c index 649eb8d1ab7d..2c01649c70f6 100644 --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1750,7 +1750,7 @@ static struct usb_midi_in_jack_descriptor *find_usb_in_jack_descriptor( struct usb_midi_in_jack_descriptor *injd = (struct usb_midi_in_jack_descriptor *)extra;

- if (injd->bLength > 4 && + if (injd->bLength >= sizeof(*injd) && injd->bDescriptorType == USB_DT_CS_INTERFACE && injd->bDescriptorSubtype == UAC_MIDI_IN_JACK && injd->bJackID == jack_id) @@ -1773,7 +1773,7 @@ static struct usb_midi_out_jack_descriptor *find_usb_out_jack_descriptor( struct usb_midi_out_jack_descriptor *outjd = (struct usb_midi_out_jack_descriptor *)extra;

- if (outjd->bLength > 4 && + if (outjd->bLength >= sizeof(*outjd) && outjd->bDescriptorType == USB_DT_CS_INTERFACE && outjd->bDescriptorSubtype == UAC_MIDI_OUT_JACK && outjd->bJackID == jack_id) @@ -1820,7 +1820,8 @@ static void snd_usbmidi_init_substream(struct snd_usb_midi *umidi, outjd = find_usb_out_jack_descriptor(hostif, jack_id); if (outjd) { sz = USB_DT_MIDI_OUT_SIZE(outjd->bNrInputPins); - iJack = *(((uint8_t *) outjd) + sz - sizeof(uint8_t)); + if (outjd->bLength >= sz) + iJack = *(((uint8_t *) outjd) + sz - sizeof(uint8_t)); } } else { /* and out jacks connect to ins */