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 BFBFFC433EF for ; Tue, 19 Apr 2022 11:02:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349044AbiDSLFP (ORCPT ); Tue, 19 Apr 2022 07:05:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229765AbiDSLFN (ORCPT ); Tue, 19 Apr 2022 07:05:13 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D214140CB for ; Tue, 19 Apr 2022 04:02:31 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id h1so945281pfv.12 for ; Tue, 19 Apr 2022 04:02:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=HPfHlnZW/J0QTwj9E3rSjp2CIkBFwM3rHUP6G621yX8=; b=iNT0C27iILY9yMw5fp4m8wrEpS19RdildApUUoPCMPAggfUSWjI1IBVhyVlsj70CLT L6utqZiifJMNTICWPPPHkUgizjX90tPr2zB5nu5K+9NmjVyYf1isJUD4lltfeoMMH0ni w+2p5Mp7SlPaWD7g+dvinXp0qtpW1YfIqFjcf1yXGYxmiWV2pYuDgydI5EtEnxa/eTYn q6nBgoXFRO5EdNI3PRrAv9w8euU/aAOiB0cCwokJBoAn1jwn2eqjQ/RDHEQQaV22zeGM fcT4jHPZP0e7NSi2CDpJ9TgGVjAfzWAXYIanuvR8OIkbRlckhD5OhuGPXRrBV1fdNl1f KrSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=HPfHlnZW/J0QTwj9E3rSjp2CIkBFwM3rHUP6G621yX8=; b=VK8Wt2TQUBKe7re5IjwVe9xCuuMddQRn7cD71YnHNUTFrNVev+VpDpwQB6q8L59Bv5 rcsnIdeJPA+3lTJenS+dn9fWSLrCLNRkzKl+9ut+QMaG6b4GEdV3Oh4iVAJotJ1hcual sx+7TLT2UVa2aHAre3vA0S9Y7pvdhbXbvdgcSnh2SrDjn/E30mOv677OpEVI4zLU+bJQ jEdwg9nq+DFBWKXKP96HelA3810nYVZvLJ/v9Y61aYN1fmwmg4w7/r3rjfFKI6ReIfii xl6oXbWbvsddgFyU98m29pIymkR6rc6uohN6aat1BMUCZfDo6d9sZtDSnh7erswK8JQe ZI6Q== X-Gm-Message-State: AOAM531VIYYhUU3f9HOIWw5cs7HmzE8jJgEtTHO0Cpcrfs2FGzSdBldF w57MJDDgJxESiBMbcgm3mVA= X-Google-Smtp-Source: ABdhPJw2iYD4KBeGw1t2OjioGfEiU3FCIpVJNOBj87m8tve6GdGwt06U40Bh5rLvaoS3a/5BfnkHrw== X-Received: by 2002:a63:1510:0:b0:39d:7212:8500 with SMTP id v16-20020a631510000000b0039d72128500mr13534063pgl.377.1650366150920; Tue, 19 Apr 2022 04:02:30 -0700 (PDT) Received: from [192.168.50.247] ([103.84.139.165]) by smtp.gmail.com with ESMTPSA id ch10-20020a056a00288a00b0050a51a95e91sm10386370pfb.201.2022.04.19.04.02.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Apr 2022 04:02:30 -0700 (PDT) Message-ID: <0da7b5da-6fab-ab73-5748-ae270d77b4d0@gmail.com> Date: Tue, 19 Apr 2022 19:02:24 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] misc: ocxl: fix possible double free in ocxl_file_register_afu Content-Language: en-US To: Frederic Barrat , ajd@linux.ibm.com, arnd@arndb.de, gregkh@linuxfoundation.org, mpe@ellerman.id.au, alastair@d-silva.org Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20220418085758.38145-1-hbh25y@gmail.com> From: Hangyu Hua In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/19 17:09, Frederic Barrat wrote: > > > On 18/04/2022 10:57, Hangyu Hua wrote: >> info_release() will be called in device_unregister() when info->dev's >> reference count is 0. So there is no need to call ocxl_afu_put() and >> kfree() again. >> >> Fix this by adding free_minor() and return to err_unregister error path. >> >> Fixes: 75ca758adbaf ("ocxl: Create a clear delineation between ocxl >> backend & frontend") >> Signed-off-by: Hangyu Hua >> --- > > > Thanks for fixing that error path! > I'm now thinking it would be cleaner to have the call to free_minor() in > the info_release() callback but that would be another patch. > In any case: > Acked-by: Frederic Barrat > >   Fred > I think it is a good idea to use callbacks to handle all garbage collections. And free_minor is used only in ocxl_file_register_afu() andocxl_file_unregister_afu(). So this should only require minor changes. Thanks. > >>   drivers/misc/ocxl/file.c | 2 ++ >>   1 file changed, 2 insertions(+) >> >> diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c >> index d881f5e40ad9..6777c419a8da 100644 >> --- a/drivers/misc/ocxl/file.c >> +++ b/drivers/misc/ocxl/file.c >> @@ -556,7 +556,9 @@ int ocxl_file_register_afu(struct ocxl_afu *afu) >>   err_unregister: >>       ocxl_sysfs_unregister_afu(info); // safe to call even if >> register failed >> +    free_minor(info); >>       device_unregister(&info->dev); >> +    return rc; >>   err_put: >>       ocxl_afu_put(afu); >>       free_minor(info);