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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS 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 C7A02C43387 for ; Sun, 23 Dec 2018 14:02:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91B2F2184D for ; Sun, 23 Dec 2018 14:02:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tronnes.org header.i=@tronnes.org header.b="cJmkKUJq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728635AbeLWN4B (ORCPT ); Sun, 23 Dec 2018 08:56:01 -0500 Received: from smtp.domeneshop.no ([194.63.252.55]:33666 "EHLO smtp.domeneshop.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725829AbeLWN4B (ORCPT ); Sun, 23 Dec 2018 08:56:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tronnes.org; s=ds201810; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=/zCb4irDvh4U99oxlMnhdzYukA3Ah2MHqRO/sIp0QxM=; b=cJmkKUJqo2quQNiTqTcE53AP1kcwgIdPg661snUTX5XmMdxaZSSQ08Wm8wm9az4+AJzsj/YHS8D6sFPV32OYQr5MQ9/P9DZQN1atBymK2Y2aUNeFIOy1m9y615rk9Nfh8XPhGl0CcY98b+6/RmQjmWKluQvUWzKPSHKDjE8m+DkteFhgrzKZzBXFgMGrPwyivNbmxLK7V2hjzCFxErEIlA1ZaeaLH7GYnb1F19VTXafy9TQIZ9LMqeINSWB+VZsiOn9kj7oXycZbgPMjB0POWaah+VE25ffCcERyH8u1C6RZ0eVn2bHwOGDTr4geq4hHUjaF8F5wzoKtyvWHTIM4TQ==; Received: from 211.81-166-168.customer.lyse.net ([81.166.168.211]:65010 helo=[192.168.10.173]) by smtp.domeneshop.no with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1gb4EZ-0008Ol-Ea; Sun, 23 Dec 2018 14:55:59 +0100 Subject: Re: [PATCH] drm/fb-helper: fix leaks in error path of drm_fb_helper_fbdev_setup To: Peter Wu , dri-devel@lists.freedesktop.org Cc: Linus Torvalds , rong.a.chen@intel.com, kraxel@redhat.com, Daniel Vetter , Linux List Kernel Mailing , lkp@01.org References: <20181223004315.GA11455@al> <20181223005507.28328-1-peter@lekensteyn.nl> From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= Message-ID: Date: Sun, 23 Dec 2018 14:55:52 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <20181223005507.28328-1-peter@lekensteyn.nl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Den 23.12.2018 01.55, skrev Peter Wu: > After drm_fb_helper_fbdev_setup calls drm_fb_helper_init, > "dev->fb_helper" will be initialized (and thus drm_fb_helper_fini will > have some effect). After that, drm_fb_helper_initial_config is called > which may call the "fb_probe" driver callback. > > This driver callback may call drm_fb_helper_defio_init (as is done by > drm_fb_helper_generic_probe) or set a framebuffer (as is done by bochs) > as documented. These are normally cleaned up on exit by > drm_fb_helper_fbdev_teardown which also calls drm_fb_helper_fini. > > If an error occurs after "fb_probe", but before setup is complete, then > calling just drm_fb_helper_fini will leak resources. This was triggered > by df2052cc922 ("bochs: convert to drm_fb_helper_fbdev_setup/teardown"): > > [ 50.008030] bochsdrmfb: enable CONFIG_FB_LITTLE_ENDIAN to support this framebuffer > [ 50.009436] bochs-drm 0000:00:02.0: [drm:drm_fb_helper_fbdev_setup] *ERROR* fbdev: Failed to set configuration (ret=-38) > [ 50.011456] [drm] Initialized bochs-drm 1.0.0 20130925 for 0000:00:02.0 on minor 2 > [ 50.013604] WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_mode_config.c:477 drm_mode_config_cleanup+0x280/0x2a0 > [ 50.016175] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G T 4.20.0-rc7 #1 > [ 50.017732] EIP: drm_mode_config_cleanup+0x280/0x2a0 > ... > [ 50.023155] Call Trace: > [ 50.023155] ? bochs_kms_fini+0x1e/0x30 > [ 50.023155] ? bochs_unload+0x18/0x40 > > This can be reproduced with QEMU and CONFIG_FB_LITTLE_ENDIAN=n. > > Link: https://lkml.kernel.org/r/20181221083226.GI23332@shao2-debian > Link: https://lkml.kernel.org/r/20181223004315.GA11455@al > Fixes: 8741216396b2 ("drm/fb-helper: Add drm_fb_helper_fbdev_setup/teardown()") > Reported-by: kernel test robot > Cc: Noralf Trønnes > Signed-off-by: Peter Wu > --- > drivers/gpu/drm/drm_fb_helper.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index 9d64f874f965..432e0f3b9267 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -2860,7 +2860,7 @@ int drm_fb_helper_fbdev_setup(struct drm_device *dev, > return 0; > > err_drm_fb_helper_fini: > - drm_fb_helper_fini(fb_helper); > + drm_fb_helper_fbdev_teardown(dev); This change will break the error path for drm_fbdev_generic_setup() because drm_fb_helper_generic_probe() cleans up on error but doesn't clear drm_fb_helper->fb resulting in a double drm_framebuffer_remove(). My assumption has been that the drm_fb_helper_funcs->fb_probe callback cleans up its resources on error. Clearly this is not the case for bochs, so my take on this is that bochsfb_create() needs to clean up on error. Gerd has a patchset that switches bochs over to the generic fbdev emulation, but ofc that doesn't help with 4.20: https://patchwork.freedesktop.org/series/54269/ Noralf. > > return ret; > } >