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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45F96C43219 for ; Wed, 18 May 2022 12:30:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236699AbiERMaa (ORCPT ); Wed, 18 May 2022 08:30:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236867AbiERM3r (ORCPT ); Wed, 18 May 2022 08:29:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F26E195795; Wed, 18 May 2022 05:28:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 240FD6164C; Wed, 18 May 2022 12:28:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44938C34119; Wed, 18 May 2022 12:28:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652876891; bh=2G3O/BeuOB/LP+pXY8WjpNyQcb0iZ9J+DrQIeLIcGXY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=boOUcq/+nlWQEoFW6WOugy+AXfoip8MtHPwSJ2jzQu5iucQZa6ZHqkvuUPd8gV1cv SEIeJ9Rr5K6MXJ8AYXtRY740YD+OBB1AKHjjCSCRGzkxuOVw+8IXKTQIsUBe4T6SdW YN9L02OCFTmew9kz+//gRD0qJca91EUxGD5p2k06Ztj43S1p0GMcN9psuQkQ8HNTzT umPjyzoAWkQ+OOBODwIVGr/+aVG7mMVUJK8N90HciP2/CPjKQ6ycoE5vCU4nHtAzOX jFycRdjAA40VGdSiLOdnHH0hrbvo1uesHAvTtvOAd1W9+ifVlF3BTTDB/zGLVUKw7H HpEmhdlE2P89Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Daniel Vetter , Daniel Vetter , Javier Martinez Canillas , Thomas Zimmermann , Sasha Levin , daniel@ffwll.ch, deller@gmx.de, wangqing@vivo.com, sam@ravnborg.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.15 07/17] fbdev: Prevent possible use-after-free in fb_release() Date: Wed, 18 May 2022 08:27:41 -0400 Message-Id: <20220518122753.342758-7-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220518122753.342758-1-sashal@kernel.org> References: <20220518122753.342758-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Vetter [ Upstream commit 89bfd4017e58faaf70411555e7f508495114e90b ] Most fbdev drivers have issues with the fb_info lifetime, because call to framebuffer_release() from their driver's .remove callback, rather than doing from fbops.fb_destroy callback. Doing that will destroy the fb_info too early, while references to it may still exist, leading to a use-after-free error. To prevent this, check the fb_info reference counter when attempting to kfree the data structure in framebuffer_release(). That will leak it but at least will prevent the mentioned error. Signed-off-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220505220413.365977-1-javierm@redhat.com Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/fbsysfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index 65dae05fff8e..ce699396d6ba 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -80,6 +80,10 @@ void framebuffer_release(struct fb_info *info) { if (!info) return; + + if (WARN_ON(refcount_read(&info->count))) + return; + kfree(info->apertures); kfree(info); } -- 2.35.1