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 5AAD0C433F5 for ; Wed, 18 May 2022 12:27:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236481AbiERM1O (ORCPT ); Wed, 18 May 2022 08:27:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236438AbiERM1D (ORCPT ); Wed, 18 May 2022 08:27:03 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D56056FD38; Wed, 18 May 2022 05:27:02 -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 ams.source.kernel.org (Postfix) with ESMTPS id 7E83AB81F40; Wed, 18 May 2022 12:27:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BC80C385AA; Wed, 18 May 2022 12:26:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652876820; bh=Y3HnaIdwRzgm8ZRIpbxNDktGkEgObnYgq8LHzhYZ0eI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YEtTQDy1ls12EXMY2VUAn9vTOABUghXAcdTppGrVNbRG5+Rm4O66odduxQLaBRZSs +esDo8m2vLki+p17KcHqhMRgL7nJFbtZx124q324AU4XBZSck+K4EiPZZZbLJnCq3E JICw+/G9IXDHw+vE7JwBlgiQScbbhFS3uOcegWFmOlI0M1JELornrmpywxATyUIipI AlxaKkPR4yE1UG0V/A2aTKTDprNQvSew6kwhRq2s35x05duin4RT0EZoISSHYAXb9A DXG2R9tVcgG4c89rZGo6Bb6X+21bzBK19sSQwMb8qyXSH+waGX/w3x97OEeJGe2xeJ mrUjZgW2hzEww== 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, thunder.leizhen@huawei.com, xiyuyang19@fudan.edu.cn, willy@infradead.org, alexander.deucher@amd.com, penguin-kernel@i-love.sakura.ne.jp, deng.changcheng@zte.com.cn, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.17 07/23] Revert "fbdev: Make fb_release() return -ENODEV if fbdev was unregistered" Date: Wed, 18 May 2022 08:26:20 -0400 Message-Id: <20220518122641.342120-7-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220518122641.342120-1-sashal@kernel.org> References: <20220518122641.342120-1-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-fbdev@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 10a9369c9dea..00f0f282e7a1 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1438,10 +1438,7 @@ 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