From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B366D17B4E9 for ; Mon, 7 Oct 2024 13:51:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728309086; cv=none; b=Orxddwbg9ETGISBcSXwLJ/1l7H3SoX03/L9jGQd3tmtkUaA4RJ0micBiOkcrjHCmJXTXz2foxRx0gx9nHoKCFiHbFFB3NXvpI95XZjqyoqLE/oHUtmfp0Mi4B8n7LOL9Bv9neJcxm6ODM+mzeKfcKH+u5EoeyZVIGzdpi1VzSSs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728309086; c=relaxed/simple; bh=Af38W6K14UukOEOgx0/mvgFmNDN3th5anBo4M2ARqD8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OSuiZ23g4pO7xQmJ/u2FsRTXtGDtwHNkAlwcZvrWQX/wDzQvdCjNTZkQFzbAPPqJc4F0Qfyr50EUSRiY+lxcug5yQiIrdc73cCfIioGmGCEHBdar+Hpiy+inNEhQQsmH2hpbAQcN3dZJuU0YfBCDIe/Ni+xX/UYg2/79g82fETM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CYOQYw+9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CYOQYw+9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5106AC4CEC6; Mon, 7 Oct 2024 13:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728309086; bh=Af38W6K14UukOEOgx0/mvgFmNDN3th5anBo4M2ARqD8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CYOQYw+9XtOkvTunR9e38VIVowN1HzmEpxK9oazjAOIT8u+nZpZOeZd+BHJW9NAZZ ffuG0u9XKF8lbBICED9/x6YC4Vpt7/zlQaTJpWBEq4uiiUuyRvhLn+N9LOgaeMeDP/ VXnhsALO+3r57KtWSGLtebuB3nuDOcoQbPC2lUAJqOYkC8TqVnCO98oZmRwXNeWiis vPSMS0ca1LAPd3KcwpVQgX9PK4PJSTuBtp6z4hcsFc0Gm6/8w4lfAC1ay6sduoqTN/ hn61yCmMmifgqJSeoy1ey1MJ1Zk6CWZZnqKf2unlTW0P2ur/TT2gozgx1sMC2US0/c 9IjSzIHTFuYAQ== Date: Mon, 7 Oct 2024 15:51:19 +0200 From: Danilo Krummrich To: Yonatan Maman Cc: nouveau@lists.freedesktop.org, Gal Shalom , kherbst@redhat.com, lyude@redhat.com, dakr@redhat.com, airlied@gmail.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] nouveau/dmem: Fix memory leak in `migrate_to_ram` upon copy error Message-ID: References: <20240923135449.356244-1-Ymaman@Nvidia.com> <20240923135449.356244-3-Ymaman@Nvidia.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Oct 07, 2024 at 03:28:22PM +0300, Yonatan Maman wrote: > > > On 30/09/2024 14:20, Danilo Krummrich wrote: > > External email: Use caution opening links or attachments > > > > > > On Mon, Sep 23, 2024 at 01:54:58PM +0000, Yonatan Maman wrote: > > > A copy push command might fail, causing `migrate_to_ram` to return a > > > dirty HIGH_USER page to the user. > > > > > > This exposes a security vulnerability in the nouveau driver. To prevent > > > memory leaks in `migrate_to_ram` upon a copy error, allocate a zero > > > page for the destination page. > > > > So, you refer to the case where this function fails in nouveau_dmem_copy_one()? > > > > If so, can you please explain why adding __GFP_ZERO to alloc_page_vma() helps > > with that? > > > > The nouveau_dmem_copy_one function ensures that the copy push command is > sent to the device firmware but does not track whether it was executed > successfully. > > In the case of a copy error (e.g., firmware or hardware error), the command > will be sent in the firmware channel, and nouveau_dmem_copy_one might > succeed, as well as the migrate_to_ram function. Thus, a dirty page could be > returned to the user. > > It’s important to note that we attempted to use nouveau_fence_wait status to > handle migration errors, but it does not catch all error types. > > To avoid this vulnerability, we allocate a zero page. So that, in case of an > error, a non-dirty (zero) page will be returned to the user. I see, I got confused by calling this a 'memory leak'. Please add this description in the commit message and avoid the term 'memory leak' in this context. > > > > > > > Signed-off-by: Yonatan Maman > > > Signed-off-by: Gal Shalom > > > > Since this is a bug, please also add a 'Fixes' tag, CC stable and add a > > 'Co-developed-by' tag if appropriate. > > sure, thanks, I will add, and push it as V2 patch-series. > > > > > --- > > > drivers/gpu/drm/nouveau/nouveau_dmem.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c > > > index 6fb65b01d778..097bd3af0719 100644 > > > --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c > > > +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c > > > @@ -193,7 +193,7 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf) > > > if (!spage || !(src & MIGRATE_PFN_MIGRATE)) > > > goto done; > > > > > > - dpage = alloc_page_vma(GFP_HIGHUSER, vmf->vma, vmf->address); > > > + dpage = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vmf->vma, vmf->address); > > > if (!dpage) > > > goto done; > > > > > > -- > > > 2.34.1 > > > >