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 X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6452C43457 for ; Wed, 14 Oct 2020 19:40:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62644214D8 for ; Wed, 14 Oct 2020 19:40:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jIqFCyoO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728780AbgJNTkj (ORCPT ); Wed, 14 Oct 2020 15:40:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726115AbgJNTkj (ORCPT ); Wed, 14 Oct 2020 15:40:39 -0400 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24C6AC061755; Wed, 14 Oct 2020 12:40:39 -0700 (PDT) Received: by mail-ed1-x542.google.com with SMTP id l16so697120eds.3; Wed, 14 Oct 2020 12:40:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=lRMFdmQbJ5RahqqzJGdCdnXN6VjpqgrM3/AzM/NSqzs=; b=jIqFCyoO2QgQafSwkepnJAuwDFR6kAlaIBpaKFCSVsIbm3U4IRiuFqrWQK/UuJuETb XW2xwse1CbW9hDpK+y5urtEIaZSCf7qMQrl9yeCUxzRp4wJ+eEXlyB5V1keoqkR9VICq TG9/oUhge2if8N+DcKMuPw8NQ8ahJiNGsgTwszuj+RxPOh1sYgLssl8BqzU4osOn9Fri D5G+QvbdTQfx9C/ueCNid5ERfp5VRa6FtjTUt6Q6D2GZf32NtMXbH4UPx+JwR5bM660S /DxCztcH4G3ITPSHS/9slHk1kjkfhBCE4XYEEo2GTS1O4pRihlFmFjrApnCle24ATl+A V6mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=lRMFdmQbJ5RahqqzJGdCdnXN6VjpqgrM3/AzM/NSqzs=; b=Yda9yJAnrD+2VdzwI3IM2kuVYB5cAsafkhuU0jC/kjXnfADVEgNAZlUzshkKq4msc6 Sd9UXjH94LBnSFE0/3UuHWo9aOcqbIJRR+xLWHIEQqCnBDPttNXE1fbVap/4SnUQSgns 2tcwN7DDQgGwGJQrP0is5GwCKojL31r2QOYoV8ZNivlH/aY7ZVSqHsvjvtT9aggA/gfO 2cFAo0eeL0Brjn6PkRfOliN5kavP1yQVNgom50W2Pwvv+EDCJ+RkAmfbRAYngeVma8/8 mmwZECcpcjlpErQOKuYGu5AKkXQo2NNlM4nz8bSOs1mK1yzrxWAvYa+lkKwObBVc1nw+ oP5Q== X-Gm-Message-State: AOAM533o6Z3uA0k3TxPlpT1eJm0leW7T438tqZqiJOT+okyKilPkprMy gYLQhjXKxAv+3C/TJEQccEA= X-Google-Smtp-Source: ABdhPJwTlkidij8uzIBt8afLdP/uVjlMjEX+Qn4s95C4fiJXGrEN7a7XveWZy1IMuR1OgdD8M0N45A== X-Received: by 2002:a50:ee19:: with SMTP id g25mr622258eds.160.1602704437708; Wed, 14 Oct 2020 12:40:37 -0700 (PDT) Received: from skbuf ([188.26.174.215]) by smtp.gmail.com with ESMTPSA id x2sm258225edr.65.2020.10.14.12.40.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2020 12:40:37 -0700 (PDT) Date: Wed, 14 Oct 2020 22:40:35 +0300 From: Vladimir Oltean To: Lukas Wunner Cc: Florian Fainelli , "linux-kernel@vger.kernel.org" , linux-spi , Mark Brown Subject: Re: Use after free in bcm2835_spi_remove() Message-ID: <20201014194035.ukduovokggu37uba@skbuf> References: <20201014140912.GB24850@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201014140912.GB24850@wunner.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 14, 2020 at 04:09:12PM +0200, Lukas Wunner wrote: > Apparently the problem is that spi_unregister_controller() drops the > last ref on the controller, causing it to be freed, and afterwards we > access the controller's private data, which is part of the same > allocation as struct spi_controller: > > bcm2835_spi_remove() > spi_unregister_controller() > device_unregister() > put_device() > spi_controller_release() # spi_master_class.dev_release() > kfree(ctlr) > bcm2835_dma_release(ctlr, bs) > ... Also see these threads: https://lore.kernel.org/linux-spi/20200922112241.GO4792@sirena.org.uk/T/#t https://lore.kernel.org/linux-spi/270b94fd1e546d0c17a735c1f55500e58522da04.camel@suse.de/T/#u And here's how _not_ to fix it: https://lore.kernel.org/linux-spi/160088764365.36195.16185348610086043664.b4-ty@kernel.org/T/#t At least without some care to not break other things: https://lore.kernel.org/linux-spi/20200928080432.GC11648@pengutronix.de/T/#t