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Date: Mon, 19 Oct 2026 08:44:45 +0200
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Yu Zhang <yuz08559@gmail.com>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] usb: gadget: u_serial: use-after-free of gserial in
 gs_write()/gs_flush_chars() remote-wakeup path
Message-ID: <2026101924-scratch-ripcord-03cd@gregkh>
References: <20261019033446.73554-1-yuz08559@gmail.com>
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In-Reply-To: <20261019033446.73554-1-yuz08559@gmail.com>

On Mon, Oct 19, 2026 at 01:34:46PM +1000, Yu Zhang wrote:
> Hi,
> 
> gs_write() and gs_flush_chars() cache
> 
> 	struct gserial *gser = port->port_usb;
> 
> at function entry, before taking port->port_lock. In the
> "if (port->suspended)" branch they drop port_lock and call
> gserial_wakeup_host(gser) on that cached pointer, with no re-check of
> port->port_usb -- unlike the sibling gs_start_tx() path in the very same
> functions, which is guarded by "if (port->port_usb)" after re-acquiring
> the lock.

Great, can you submit a patch for this after testing this on linux-next
to verify it's not already resolved?

thanks,

greg k-h