From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 66DFD4D2ECC; Mon, 19 Oct 2026 10:28:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792405709; cv=none; b=m8GI/AjBuqKgxne/I6DPlVxyYYhv3so89byO3Jmcjuxhsxs5xtq7zE4vcMxmvq63ukzSAhqN2x3GOAyPuZ51jr7umWRxFd625ebYviU7+F6Qtvr6d3iP0fvhBl6c9HkzyVSvBdUGk4L2RWUTkUmx+NlkqgrERZBIZO5aHrBYOyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792405709; c=relaxed/simple; bh=4qz8eMfz+Jo1KHqS+s17rqoQGTMxaqrvVFecgZkRitY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mt6cTg3Y4X8PRUWNrR5so7RezW4ps50OaEFPVLAohsJ/mBYfbjfEWn4H21Q8Wn4K9g0n0thrOhlRB9QkfXhye0ywoTi/K5AM2LM0HF6doCUGWcRFJZ5F3uXUKsYaqQS5hTSFu+r9s1LbmfnqN28kGbaN/DWGk1AzoEouk/yaFTc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UC8edqst; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UC8edqst" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD15D1F000C5; Mon, 19 Oct 2026 10:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792405707; bh=4qz8eMfz+Jo1KHqS+s17rqoQGTMxaqrvVFecgZkRitY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=UC8edqst7rNXAAiHSudn8cE0SpHqwN5mu0IRB3MwqLGkD4KLbdFBkbNH+63YAa1y7 aB2CGqfzuNLYUEeT7JZIUtNoEZMBSJ6iyAPTMSCQsYF4/AAHox96ASbSzDYTJW1dmf r4yHjsTqITpUsaDtORjeVdJGfu02BatGj4FERcrGXxT/BNOIPjhqDBMeYE5HqSf9ZC MJyzB67rq1gV2S1IuV8mXA0njjcPsR/nrwLbdxzV/KFU9Z0RF2UCMM20X0AkfD/c+L zCM4jmT0i+R+hEmaGK6bIQEJ6Nn9LUGG32qhCE7uUShFSd3ABoWIUuoqKSaHcuh9H4 PhldKIEJMV43A== Date: Mon, 19 Oct 2026 11:28:23 +0100 From: "Lorenzo Stoakes (ARM)" To: David Carlier Cc: Andrew Morton , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Jaroslav Kysela , Takashi Iwai , Kazuki Hanai , linux-mm@kvack.org, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 16/39] mm/vma: only allow mmap to clear VMA_MAYWRITE_BIT if not mm-managed Message-ID: References: <20261013-b4-mmap-prepare-vma-flag-sanify-v6-16-1aa3c9b139f9@kernel.org> <20261018025905.201296-1-devnexen@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261018025905.201296-1-devnexen@gmail.com> On Sun, Oct 18, 2026 at 03:59:05AM +0100, David Carlier wrote: > Hi Lorenzo, > > I think one site was missed: usb_stream_hwdep_mmap() in > sound/usb/usx2y/us122l.c clears VM_MAYWRITE on the read buffer since > 71c610aeb177 ("ALSA: us122l: Prevent write upgrades for read mappings"), > but sets neither VM_PFNMAP nor VM_MIXEDMAP (pages come from .fault via > vmf->page, like the PCM status page in 13/39). > > So a MAP_PRIVATE mapping of the read buffer, or MAP_SHARED on an O_RDWR > fd, now hits the WARN_ON_ONCE in mmap_validate() and fails with -EINVAL. > > The VM_MAYWRITE clear is a security fix, and the VMA must stay > expandable for mremap(), so converting it like 13/39 or setting > VM_MIXEDMAP seems the way to go. > > Found by code reading, not tested on hardware. Thanks. I will check it. Somebody doing something broken as a fix is fun. It might be better to fix that with a separate patch, I don't think it really makes sense to add a brand new patch to this series just for that. I will follow that up. -- Cheers, Lorenzo