From patchwork Thu May 5 21:59:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Javier Martinez Canillas X-Patchwork-Id: 570048 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 CB2CCC433F5 for ; Thu, 5 May 2022 22:00:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358460AbiEEWEA (ORCPT ); Thu, 5 May 2022 18:04:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377701AbiEEWDx (ORCPT ); Thu, 5 May 2022 18:03:53 -0400 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [170.10.133.74]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DCCF45C743 for ; Thu, 5 May 2022 15:00:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651788009; 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; bh=g7o/PcjByL5k08SmN+MKIpgdp4lhrjdKDcCDQqkuG3g=; b=ILJ7hGUaV9x5/jQ9AZ+5lR6KPBetiFC7g44LbfsbAvW8QdGuAo/RzYW5Zupxd5XZwuyg2e 8tzO9yQMXcAEvqHkE1ylcg4192NtH1PgPfSjjGOJ/dKx4+ILBF5OzdrHZ9eNtHWcofTwPc t2v2sY41HlGD7dPLM8avG+u56ZdFctc= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-478-nUiLOTU2MOmwShig7K0yVg-1; Thu, 05 May 2022 18:00:08 -0400 X-MC-Unique: nUiLOTU2MOmwShig7K0yVg-1 Received: by mail-wm1-f72.google.com with SMTP id v184-20020a1cacc1000000b00393e492a398so5096210wme.5 for ; Thu, 05 May 2022 15:00:08 -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:mime-version :content-transfer-encoding; bh=g7o/PcjByL5k08SmN+MKIpgdp4lhrjdKDcCDQqkuG3g=; b=ypyMamiv2lqZaQtx7/salw3OvNADs90qZpnpyVnZ+Lzw7MhRWJ8muDFLncue5WYbtK mffM97u02EnfwpAdtTDv4QMvkKwJ2egmy7uh0/X81nHgjOvaVtpBg/q72alValsg3H9k rCZp/DOhr8qtXdUIM00kVS++YPKpwdc6aWIJ1c1u3S9iOiZgp/Wty69TrCKPlyaTwjIO fujz3o6X0bl4AHRLyQc3mTnqdMSnJ/buOE66mM9Yznr2jov+J4yMR1EWW0Q/ulur0JHl 6AJAxcbfkw67lcFNCypCO3UxYnU1+LDOBlEabht5b6ma1lmEKK9cmvKwEqbmdQeX1g7/ 9g5w== X-Gm-Message-State: AOAM530/UxI17UhtENtGdPmwK96BhLspnLZNQvhIKywpAwHIvxbbHTFT vWYT9fpSt1S2CbTdCTmfS9940HWfPHvzIfy+YkJswrSg5rUv2Ge6/VrVQFooHeshLTPI+88D3LC DNJF9u/sjPST62UUp1SSONHY= X-Received: by 2002:a05:6000:1815:b0:20a:deee:3cf0 with SMTP id m21-20020a056000181500b0020adeee3cf0mr154921wrh.210.1651788006924; Thu, 05 May 2022 15:00:06 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzk9nG54+YuJURc6OI8oVH2TrMJldwkCWvspEI1wXTQzvXeoooK0kqJvqJXa5/C6tS1lOzpJQ== X-Received: by 2002:a05:6000:1815:b0:20a:deee:3cf0 with SMTP id m21-20020a056000181500b0020adeee3cf0mr154910wrh.210.1651788006661; Thu, 05 May 2022 15:00:06 -0700 (PDT) Received: from minerva.home (205.pool92-176-231.dynamic.orange.es. [92.176.231.205]) by smtp.gmail.com with ESMTPSA id 25-20020a05600c029900b003942a244ed1sm2271241wmk.22.2022.05.05.15.00.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 May 2022 15:00:06 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: Javier Martinez Canillas , Daniel Vetter , Hans de Goede , Helge Deller , Peter Jones , Thomas Zimmermann , Zack Rusin , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH v3 0/4] fbdev: Fix use-after-free caused by wrong fb_info cleanup in drivers Date: Thu, 5 May 2022 23:59:43 +0200 Message-Id: <20220505215947.364694-1-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Hello, This series contains patches suggested by Daniel Vetter to fix a use-after-free error in the fb_release() function, due a fb_info associated with a fbdev being freed too early while a user-space process still has the fbdev dev node opened. That is caused by a wrong management of the struct fb_info lifetime in drivers, but the fbdev core can also be made more resilient about it an leak This can easily be reproduced with the simplefb driver doing the following: $ cat < /dev/fb0 & $ echo simple-framebuffer.0 > /sys/bus/platform/drivers/simple-framebuffer/unbind $ kill %1 [ 257.490471] ------------[ cut here ]------------ ... [ 257.495125] refcount_t: underflow; use-after-free. [ 257.495222] WARNING: CPU: 0 PID: 975 at lib/refcount.c:28 refcount_warn_saturate+0xf4/0x144 ... [ 257.637482] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 257.644441] pc : refcount_warn_saturate+0xf4/0x144 [ 257.649226] lr : refcount_warn_saturate+0xf4/0x144 [ 257.654009] sp : ffff80000a06bbf0 [ 257.657315] x29: ffff80000a06bbf0 x28: 000000000000000a x27: 000000000000000a [ 257.664448] x26: 0000000000000000 x25: ffff470b88c6a180 x24: 000000000000000a [ 257.671581] x23: ffff470b81706480 x22: ffff470b808c2160 x21: ffff470b8922ba20 [ 257.678713] x20: ffff470b891f5810 x19: ffff470b891f5800 x18: ffffffffffffffff [ 257.685846] x17: 3a725f7463656a62 x16: ffffbb18c6465fd4 x15: 0720072007200720 [ 257.692978] x14: 0720072d072d072d x13: 0a2e656572662d72 x12: 657466612d657375 [ 257.700110] x11: 203b776f6c667265 x10: 646e75203a745f74 x9 : ffffbb18c58f6c90 [ 257.707242] x8 : 75203b776f6c6672 x7 : 65646e75203a745f x6 : 0000000000000001 [ 257.714373] x5 : ffff470bff8ec418 x4 : 0000000000000000 x3 : 0000000000000027 [ 257.721506] x2 : 0000000000000000 x1 : 0000000000000027 x0 : 0000000000000026 [ 257.728638] Call trace: [ 257.731075] refcount_warn_saturate+0xf4/0x144 [ 257.735513] put_fb_info+0x70/0x7c [ 257.738916] fb_release+0x60/0x74 [ 257.742225] __fput+0x88/0x240 [ 257.745276] ____fput+0x1c/0x30 [ 257.748410] task_work_run+0xc4/0x21c [ 257.752066] do_exit+0x170/0x370 [ 257.755288] do_group_exit+0x40/0xb4 [ 257.758858] get_signal+0x8e0/0x90c [ 257.762339] do_signal+0x1a0/0x280 [ 257.765733] do_notify_resume+0xc8/0x390 [ 257.769650] el0_da+0xe8/0xf0 [ 257.772613] el0t_64_sync_handler+0xe8/0x130 [ 257.776877] el0t_64_sync+0x190/0x194 [ 257.780534] ---[ end trace 0000000000000000 ]--- Patch #1 adds a WARN_ON() to framebuffer_release() to prevent the use-after-free to happen. Patch #2, #3 and #4 fix the simplefb, efifb and vesafb drivers respectively, to free the resources at the correct place. Changes in v3: - Add Fixes: tag (Daniel Vetter). - Include in commit message a note that drivers are still broken but at least reverts to the previous behavior (Daniel Vetter). - Only move framebuffer_release() and don't do any other change (Daniel Vetter). Changes in v2: - Also do the change for vesafb (Thomas Zimmermann). Daniel Vetter (1): fbdev: Prevent possible use-after-free in fb_release() Javier Martinez Canillas (3): fbdev: simplefb: Cleanup fb_info in .fb_destroy rather than .remove fbdev: efifb: Cleanup fb_info in .fb_destroy rather than .remove fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove drivers/video/fbdev/core/fbsysfs.c | 4 ++++ drivers/video/fbdev/efifb.c | 9 ++++++++- drivers/video/fbdev/simplefb.c | 8 +++++++- drivers/video/fbdev/vesafb.c | 8 +++++++- 4 files changed, 26 insertions(+), 3 deletions(-)