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 5D9A0C433F5 for ; Wed, 18 May 2022 12:32:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236728AbiERMc2 (ORCPT ); Wed, 18 May 2022 08:32:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236886AbiERMaR (ORCPT ); Wed, 18 May 2022 08:30:17 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 052D114D7AB; Wed, 18 May 2022 05:28:44 -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 28DEF61688; Wed, 18 May 2022 12:28:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E517EC34115; Wed, 18 May 2022 12:28:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652876887; bh=iKQ0hZxnLPgEJ50DVj3I4D8Qng3oKsd31mCAqKdvhDo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gbVJvYKBaEO77WQHWyHmDbwPpo7yzm4MJMOwcWj0FqG7LWLTvbABpqVxRN2NmF86B sW81TRfB/K6Gn3f1l5SvFstjWIS6cNyTxUayblajrtJpgYqNoOs/HlLuEAjnizEDlZ ZjOMhpRdtR29d8X8GaaUzD8eiqWoxaCzYs3oNBmob4Hcmnqkyk+pLRZ2GI80UqHfDR sUCg3hWo/+rFpFkC5ZO5iPN+p9T8gZj9gguvkq4fx9ccbWBGomfOzg4n53cDycj8kt 86QlUP58phTTkLtBhkIEGVpkQiFfbSQnba2atwNr4mt4l4H8JhKekU8n+alWAbyZHY WgdKmJRpNIflw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Javier Martinez Canillas , Daniel Vetter , Sasha Levin , daniel@ffwll.ch, deller@gmx.de, sam@ravnborg.org, tzimmermann@suse.de, deng.changcheng@zte.com.cn, xiyuyang19@fudan.edu.cn, zheyuma97@gmail.com, alexander.deucher@amd.com, penguin-kernel@i-love.sakura.ne.jp, thunder.leizhen@huawei.com, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.15 06/17] Revert "fbdev: Make fb_release() return -ENODEV if fbdev was unregistered" Date: Wed, 18 May 2022 08:27:40 -0400 Message-Id: <20220518122753.342758-6-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: Javier Martinez Canillas [ Upstream commit 135332f34ba2662bc1e32b5c612e06a8cc41a053 ] This reverts commit aafa025c76dcc7d1a8c8f0bdefcbe4eb480b2f6a. That commit attempted to fix a NULL pointer dereference, caused by the struct fb_info associated with a framebuffer device to not longer be valid when the file descriptor was closed. The issue was exposed by commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal"), which added a new path that goes through the struct device removal instead of directly unregistering the fb. 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. This meant that due to this switch, the fb_info was now destroyed too early, while references still existed, while before it was simply leaked. The patch we're reverting here reinstated that leak, hence "fixed" the regression. But the proper solution is to fix the drivers to not release the fb_info too soon. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220504115917.758787-1-javierm@redhat.com Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/fbmem.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 8e38a7a5cf2f..0371ad233fdf 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1436,10 +1436,7 @@ fb_release(struct inode *inode, struct file *file) __acquires(&info->lock) __releases(&info->lock) { - struct fb_info * const info = file_fb_info(file); - - if (!info) - return -ENODEV; + struct fb_info * const info = file->private_data; lock_fb_info(info); if (info->fbops->fb_release) -- 2.35.1