linux-kernel - Re: usb: gadget: Add support for USB MIDI 2.0 function driver

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] [day] [month] [year] [list]

Message-ID: <875xozi4ak.wl-tiwai@suse.de>
Date: Thu, 07 Nov 2024 14:04:03 +0100
From: Takashi Iwai <tiwai@...e.de>
To: "Colin King (gmail)" <colin.i.king@...il.com>
Cc: Takashi Iwai <tiwai@...e.de>,	Paul Cercueil <paul@...pouillou.net>,
	Simona Vetter <simona.vetter@...ll.ch>,	Christian König
 <christian.koenig@....com>,	Michael Grzeschik <m.grzeschik@...gutronix.de>,
	linux-usb@...r.kernel.org,	Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>,	"linux-kernel@...r.kernel.org"
 <linux-kernel@...r.kernel.org>
Subject: Re: usb: gadget: Add support for USB MIDI 2.0 function driver

On Thu, 07 Nov 2024 13:30:12 +0100,
Colin King (gmail) wrote:
> 
> Hi,
> 
> Static analysis has found a minor issue in the following commit:
> 
> commit 8b645922b22303cec4628dbbbf6c8553d1cdec87
> Author: Takashi Iwai <tiwai@...e.de>
> Date:   Tue Jul 25 08:22:00 2023 +0200
> 
>     usb: gadget: Add support for USB MIDI 2.0 function driver
> 
> The issue is in function f_midi2_set_alt in
> drivers/usb/gadget/function/f_midi2.c as follows:
> 
>         if (intf != midi2->midi_if || alt > 1)
>                 return 0;
> 
>         if (alt == 0)
>                 op_mode = MIDI_OP_MODE_MIDI1;
>         else if (alt == 1)
>                 op_mode = MIDI_OP_MODE_MIDI2;
>         else
>                 op_mode = MIDI_OP_MODE_UNSET;
> 
> 
> the first if statement will return if alt is 2 or more, so at the
> following cascaded if/else if/else statement alt is either 0 or 1,
> hence the final else that sets op_mode = MIDI_OP_MODE_UNSET can never
> be reached.
> 
> Either the last else statement is redundant and can be removed, or the
> first if statement needs to check for alt > 2 rather than > 1. I'm not
> sure which one is the valid fix to make. Any ideas?

We can fix in either way, as it won't happen practically :)
I guess I thought of alt < 0, but it's an unsigned int, so this is
nonsense.  I'd rather drop the redundant else statement.


thanks,

Takashi