From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AAD9C07E9C for ; Mon, 12 Jul 2021 16:50:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D14361152 for ; Mon, 12 Jul 2021 16:50:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234657AbhGLQxm (ORCPT ); Mon, 12 Jul 2021 12:53:42 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:56116 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232710AbhGLQxl (ORCPT ); Mon, 12 Jul 2021 12:53:41 -0400 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 33622CC; Mon, 12 Jul 2021 18:50:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1626108651; bh=+t8lSKMlrb/3E4DhDYLs266oy4TOU8BHEmxESYaNt8I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pieGt0ks0vsh7tOXCU6EM+lcz8G3MzzFccBJJnT/b5ufqCCDusGqc2R5SuqS5//29 pHi/RuF7RFsy5Kk37tHBmOO25wApXpjMXrepmesbJpg8L9UV+eMlx6Opni6mcpNKIB WHpc0Eb8LZOJgfZ4tpeSrSIY4PB0jwf/T5qW8Dj4= Date: Mon, 12 Jul 2021 19:50:04 +0300 From: Laurent Pinchart To: Steven Price Cc: Daniel Vetter , David Airlie , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Biju Das Subject: Re: [PATCH] drm/of: free the iterator object on failure Message-ID: References: <20210712155758.48286-1-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210712155758.48286-1-steven.price@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steven, Thank you for the patch. On Mon, Jul 12, 2021 at 04:57:58PM +0100, Steven Price wrote: > When bailing out due to the sanity check the iterator value needs to be > freed because the early return prevents for_each_child_of_node() from > doing the dereference itself. > > Fixes: 4ee48cc5586b ("drm: of: Fix double-free bug") I don't think the Fixes tag is correct, the issue was already present before 4ee48cc5586b. The fix looks right though. > Signed-off-by: Steven Price > --- > drivers/gpu/drm/drm_of.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > Daniel's email[1] made me take a look at this function and it appears > that for_each_child_of_node()'s interface had caused a bad bug fix due > to the hidden reference counting in the iterator. > > [1] https://lore.kernel.org/r/YOxQ5TbkNrqCGBDJ%40phenom.ffwll.local > > diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c > index 197c57477344..997b8827fed2 100644 > --- a/drivers/gpu/drm/drm_of.c > +++ b/drivers/gpu/drm/drm_of.c > @@ -331,8 +331,10 @@ static int drm_of_lvds_get_remote_pixels_type( > * configurations by passing the endpoints explicitly to > * drm_of_lvds_get_dual_link_pixel_order(). > */ > - if (!current_pt || pixels_type != current_pt) > + if (!current_pt || pixels_type != current_pt) { > + of_node_put(endpoint); > return -EINVAL; > + } > } > > return pixels_type; -- Regards, Laurent Pinchart