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 3988CC433EF for ; Thu, 5 May 2022 22:06:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386183AbiEEWKU (ORCPT ); Thu, 5 May 2022 18:10:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1386177AbiEEWKS (ORCPT ); Thu, 5 May 2022 18:10:18 -0400 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [170.10.129.74]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 25E855EDDA for ; Thu, 5 May 2022 15:06:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651788396; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2QUs/dFpZjXD63m2oUdzjI7+Wpnx04uqjBRSmxR+fJo=; b=NoeVH+LQnxYMLYYVXHGRCy7OFetIWVi5u+7Pk5FBOHyKKEMSgREgymlEgh3EV5WBMV/IZK 14DKGnoqDCy80qvLrNJyR6w6p05KtLDMZMfmi8Kp7WCNuTRyjXogw+BhgFQKGeqYGr9/FG XegBqSEp0bm6RVZ4+Vinv6Aoi4AgJrc= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-639-IOYryVw9Nh6yPaHpBI4weg-1; Thu, 05 May 2022 18:06:35 -0400 X-MC-Unique: IOYryVw9Nh6yPaHpBI4weg-1 Received: by mail-wr1-f72.google.com with SMTP id s14-20020adfa28e000000b0020ac7532f08so1874160wra.15 for ; Thu, 05 May 2022 15:06:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=2QUs/dFpZjXD63m2oUdzjI7+Wpnx04uqjBRSmxR+fJo=; b=29P5oF84PWp0Z/EOyqbffA7rHLgnPZzNqyas9FjoSyi57U478h/BFTrwuAqGAh3eq/ T/futsReB6d6EBYrnD4CiH9dYc2hO6qBtq5EsqxDWXBmz2Ox9JZjm7Btb31DbvY3IcBI PFG8K3PmglOiWd/IHY6OKQU2eppea0SWar1F9TV4HjwYzcdohO1+59Xix5VK/VJ5buX/ L5y9Y1hOawZ3edDIy20ylnDDvvjMnFanHvqeuLlPsQ+ac3TPCAehJ3pf0eG0/uuFmmBV PttT9MrX9aEpe0PEl6aKCawY0GCgrJjWBYYALiTUHmWowDicPFYweejbNLaOjU2UGddl wv0w== X-Gm-Message-State: AOAM531kM0GFGkZFrlPkkAGPRMxrNoCjHSj15mrsPZSoeeFbQ7gYS7Cd MgoN22IasmrHaO4eiQursNYRi6p9cBwxO+11odaTQpZsQtGWcKPzPMy795ZAVz/Fw8RZm4aK0h8 CX14GgpMOjkhnCXaj1/BpiydWwf80647HU66YQsQvYAOTBgZSqd4g7w0ppSIJrFcSI2h2VnU9Mc 4= X-Received: by 2002:a5d:6dd1:0:b0:207:92c4:eaef with SMTP id d17-20020a5d6dd1000000b0020792c4eaefmr165085wrz.498.1651788393706; Thu, 05 May 2022 15:06:33 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwJuZtwlqObinYznGZMuIaaeVki7i2UMoMVMO9mJCvQ2FsqRQYwPdVCdFx20Il32JBmnuIcGA== X-Received: by 2002:a5d:6dd1:0:b0:207:92c4:eaef with SMTP id d17-20020a5d6dd1000000b0020792c4eaefmr165062wrz.498.1651788393466; Thu, 05 May 2022 15:06:33 -0700 (PDT) Received: from minerva.home (205.pool92-176-231.dynamic.orange.es. [92.176.231.205]) by smtp.gmail.com with ESMTPSA id n11-20020a056000170b00b0020c5253d8c7sm2040236wrc.19.2022.05.05.15.06.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 15:06:33 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, Daniel Vetter , Helge Deller , Hans de Goede , Javier Martinez Canillas , Thomas Zimmermann Subject: [PATCH v3 4/4] fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove Date: Fri, 6 May 2022 00:06:31 +0200 Message-Id: <20220505220631.366371-1-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220505215947.364694-1-javierm@redhat.com> References: <20220505215947.364694-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The driver is calling framebuffer_release() in its .remove callback, but this will cause the struct fb_info to be freed too early. Since it could be that a reference is still hold to it if user-space opened the fbdev. This would lead to a use-after-free error if the framebuffer device was unregistered but later a user-space process tries to close the fbdev fd. To prevent this, move the framebuffer_release() call to fb_ops.fb_destroy instead of doing it in the driver's .remove callback. Strictly speaking, the code flow in the driver is still wrong because all the hardware cleanupd (i.e: iounmap) should be done in .remove while the software cleanup (i.e: releasing the framebuffer) should be done in the .fb_destroy handler. But this at least makes to match the behavior before commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal"). Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann Reviewed-by: Daniel Vetter --- Changes in v3: - Only move framebuffer_release() and don't do any other change (Daniel Vetter). Changes in v2: - Also do the change for vesafb (Thomas Zimmermann). drivers/video/fbdev/vesafb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c index df6de5a9dd4c..e25e8de5ff67 100644 --- a/drivers/video/fbdev/vesafb.c +++ b/drivers/video/fbdev/vesafb.c @@ -179,6 +179,10 @@ static int vesafb_setcolreg(unsigned regno, unsigned red, unsigned green, return err; } +/* + * fb_ops.fb_destroy is called by the last put_fb_info() call at the end + * of unregister_framebuffer() or fb_release(). Do any cleanup here. + */ static void vesafb_destroy(struct fb_info *info) { struct vesafb_par *par = info->par; @@ -188,6 +192,8 @@ static void vesafb_destroy(struct fb_info *info) if (info->screen_base) iounmap(info->screen_base); release_mem_region(info->apertures->ranges[0].base, info->apertures->ranges[0].size); + + framebuffer_release(info); } static struct fb_ops vesafb_ops = { @@ -484,10 +490,10 @@ static int vesafb_remove(struct platform_device *pdev) { struct fb_info *info = platform_get_drvdata(pdev); + /* vesafb_destroy takes care of info cleanup */ unregister_framebuffer(info); if (((struct vesafb_par *)(info->par))->region) release_region(0x3c0, 32); - framebuffer_release(info); return 0; } -- 2.35.1