[PATCH 4.19 062/125] ALSA: usb-audio: Fix possible NULL dereference at create_yamaha_midi_quirk()

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit 60849562a5db4a1eee2160167e4dce4590d3eafe upstream.

The previous addition of descriptor validation may lead to a NULL
dereference at create_yamaha_midi_quirk() when either injd or outjd is
NULL.  Add proper non-NULL checks.

Fixes: 57f8770620e9 ("ALSA: usb-audio: More validations of descriptor units")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/usb/quirks.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -259,8 +259,8 @@ static int create_yamaha_midi_quirk(stru
 					NULL, USB_MS_MIDI_OUT_JACK);
 	if (!injd && !outjd)
 		return -ENODEV;
-	if (!snd_usb_validate_midi_desc(injd) ||
-	    !snd_usb_validate_midi_desc(outjd))
+	if (!(injd && snd_usb_validate_midi_desc(injd)) ||
+	    !(outjd && snd_usb_validate_midi_desc(outjd)))
 		return -ENODEV;
 	if (injd && (injd->bLength < 5 ||
 		     (injd->bJackType != USB_MS_EMBEDDED &&