linux-kernel - Re: [usb-storage] Re: [PATCH] USB: storage: Ignore driver CD mode for Realtek multi-mode Wi-Fi dongles

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 for Android: free password hash cracker in your pocket

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

Message-ID: <03d4c721-f96d-4ace-b01e-c7adef150209@rowland.harvard.edu>
Date: Wed, 13 Aug 2025 14:19:30 -0400
From: Alan Stern <stern@...land.harvard.edu>
To: Zenm Chen <zenmchen@...il.com>
Cc: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, pkshih@...ltek.com,
	rtl8821cerfe2@...il.com, stable@...r.kernel.org,
	usb-storage@...ts.one-eyed-alien.net, usbwifi2024@...il.com
Subject: Re: [usb-storage] Re: [PATCH] USB: storage: Ignore driver CD mode
 for Realtek multi-mode Wi-Fi dongles

On Thu, Aug 14, 2025 at 01:53:12AM +0800, Zenm Chen wrote:
> Alan Stern <stern@...land.harvard.edu> 於 2025年8月14日 週四 上午12:58寫道：
> >
> > On Thu, Aug 14, 2025 at 12:24:15AM +0800, Zenm Chen wrote:
> > > Many Realtek USB Wi-Fi dongles released in recent years have two modes:
> > > one is driver CD mode which has Windows driver onboard, another one is
> > > Wi-Fi mode. Add the US_FL_IGNORE_DEVICE quirk for these multi-mode devices.
> > > Otherwise, usb_modeswitch may fail to switch them to Wi-Fi mode.
> >
> > There are several other entries like this already in the unusual_devs.h
> > file.  But I wonder if we really still need them.  Shouldn't the
> > usb_modeswitch program be smart enough by now to know how to handle
> > these things?
> 
> Hi Alan,
> 
> Thanks for your review and reply.
> 
> Without this patch applied, usb_modeswitch cannot switch my Mercury MW310UH
> into Wi-Fi mode [1].

Don't post a link to a video; it's not very helpful.  Instead, copy the 
output from the usb_modeswitch program and include it in an email 
message.

> I also ran into a similar problem like [2] with D-Link
> AX9U, so I believe this patch is needed.

Maybe it is and maybe not.  It depends on where the underlying problem 
is.  If the problem is in the device then yes, the patch probably is 
needed.  But if the problem is in usb_modeswitch then the patch probably 
is not needed.

> > In theory, someone might want to access the Windows driver on the
> > emulated CD.  With this quirk, they wouldn't be able to.
> >
> 
> Actually an emulated CD doesn't appear when I insert these 2 Wi-Fi dongles into
> my Linux PC, so users cannot access that Windows driver even if this patch is not 
> applied.

What does happen when you insert the WiFi dongle?  That is, what 
messages appear in the dmesg log?

Also, can you collect a usbmon trace showing what happens when the 
dongle is plugged in?

Alan Stern