linux-kernel - Re: [PATCH 4.19 062/125] ALSA: usb-audio: Fix possible NULL dereference at create_yamaha_midi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 13 Nov 2019 11:19:54 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Takashi Iwai <tiwai@...e.de>
Subject: Re: [PATCH 4.19 062/125] ALSA: usb-audio: Fix possible NULL
 dereference at create_yamaha_midi_quirk()

Hi!

> From: Takashi Iwai <tiwai@...e.de>
> 
> 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.

This is wrong.

> @@ -259,8 +259,8 @@ static int create_yamaha_midi_quirk(stru
>  					NULL, USB_MS_MIDI_OUT_JACK);
>  	if (!injd && !outjd)
>  		return -ENODEV;

Clearly code wants to allow at most one of them to be NULL.

> -	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;

Yet it will return here if it is. Correct check would be

+     if (!(!injd || snd_usb_validate_midi_desc(injd)) ||
+         !(!outjd || snd_usb_validate_midi_desc(outjd)))

AFAICT.

Best regards,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Download attachment "signature.asc" of type "application/pgp-signature" (182 bytes)