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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 CD409C43460 for ; Tue, 27 Apr 2021 12:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BD7C61006 for ; Tue, 27 Apr 2021 12:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236163AbhD0MVM (ORCPT ); Tue, 27 Apr 2021 08:21:12 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33830 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235638AbhD0MVK (ORCPT ); Tue, 27 Apr 2021 08:21:10 -0400 Received: from 1.general.cking.uk.vpn ([10.172.193.212]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lbMhW-0004Z2-Ll; Tue, 27 Apr 2021 12:20:26 +0000 Subject: Re: [PATCH][next][V2] gpio: sim: Fix dereference of free'd pointer config To: Andy Shevchenko Cc: Linus Walleij , Bartosz Golaszewski , "open list:GPIO SUBSYSTEM" , kernel-janitors , Linux Kernel Mailing List References: <20210427114950.12739-1-colin.king@canonical.com> From: Colin Ian King Message-ID: Date: Tue, 27 Apr 2021 13:20:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/04/2021 13:11, Andy Shevchenko wrote: > On Tue, Apr 27, 2021 at 2:49 PM Colin King wrote: >> >> From: Colin Ian King >> >> The error return of config->id dereferences the kfree'd object config. >> Fix this by using a temporary variable for the id to avoid this issue. > > Thanks! > I'm wondering how I missed this... Nevertheless > > Reviewed-by: Andy Shevchenko > >> Addresses-Coverity: ("Read from pointer aftyer free") > > after > Can that be fixed before applying rather me sending a V3? >> Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier") >> Signed-off-by: Colin Ian King >> --- >> V2: Don't make id local to the if statement to improve coding style. >> Thanks to Bartosz Golaszewski for this improvement suggestion. >> --- >> drivers/gpio/gpio-sim.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c >> index 2e2e6399e453..b21541c0b700 100644 >> --- a/drivers/gpio/gpio-sim.c >> +++ b/drivers/gpio/gpio-sim.c >> @@ -744,20 +744,22 @@ static struct config_item * >> gpio_sim_config_make_item(struct config_group *group, const char *name) >> { >> struct gpio_sim_chip_config *config; >> + int id; >> >> config = kzalloc(sizeof(*config), GFP_KERNEL); >> if (!config) >> return ERR_PTR(-ENOMEM); >> >> - config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); >> - if (config->id < 0) { >> + id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); >> + if (id < 0) { >> kfree(config); >> - return ERR_PTR(config->id); >> + return ERR_PTR(id); >> } >> >> config_item_init_type_name(&config->item, name, >> &gpio_sim_chip_config_type); >> config->num_lines = 1; >> + config->id = id; >> mutex_init(&config->lock); >> >> return &config->item; >> -- >> 2.30.2 >> > >