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=-13.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,URIBL_BLOCKED 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 CF346C433B4 for ; Tue, 27 Apr 2021 11:33:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C8BC613EF for ; Tue, 27 Apr 2021 11:33:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235999AbhD0LeF (ORCPT ); Tue, 27 Apr 2021 07:34:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230270AbhD0LeD (ORCPT ); Tue, 27 Apr 2021 07:34:03 -0400 Received: from mail-yb1-xb2a.google.com (mail-yb1-xb2a.google.com [IPv6:2607:f8b0:4864:20::b2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64366C061756 for ; Tue, 27 Apr 2021 04:33:20 -0700 (PDT) Received: by mail-yb1-xb2a.google.com with SMTP id t94so15686045ybi.3 for ; Tue, 27 Apr 2021 04:33:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Lw23nfmWqVriVGK3/XB6PR3bEvWpn+m/Rvh9hTRDTtA=; b=dBVVKqSGsvYs0wXooeoT3TmjplzCzWtUnyuS9qS83f8+EyODqKDOOGiv5ZXk/3RrLV bH3UcfevrCi+nHmi2AVyA7bB0p1OrnjYfZ39Rljb4z/pVbJIP01fTTURAOCCIXbuNRRp Nid07/kTsDKp36Y+dYZSVw+MVNx51T7GNRWE8wOtqD0FE0Rl1L8BBkcVIeOBl1ora/7k yyE4/UIBbvJDU1ZYkrhZvQwAk9Vq278/B3yGpMD+GBtC135e/ZGcMHN9nKn+ctwt1THF WkKcfzqAHDKydJLprMnraSh/lC+bqeCArAIF/4Le5oG9fU4zeINRpV+uaFKNX2jWbvfs C9WA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Lw23nfmWqVriVGK3/XB6PR3bEvWpn+m/Rvh9hTRDTtA=; b=fVKgaUy7qMEhqR59H71rfACS6x2JvdJXVZHE+YU2VNnbvQRulv5CcIJbqWc1lVWIGl 7Ha3mYHCowQTlcHOyqT7ZyTaQvvPCiIEWhdQ6bIryGb00RVXdJ5PfE+AnSgnbttklFIh FuwMJsYNH7oszh7N6qIsKwtpcMiQq6PK8jxscImM9K/tu/l0NoyvrsuKNDp/8xK7eE27 C2wG5rhKlXneqppbdCHkBful7HMNLfj/waet5noShByJ8P/UKIz6EeSTfjiIBvDxp4XB NkjRpmupMdMIptiT/MdL2aGenkdu7m+wOnmBwiwET1Mq9uID15IPItPMDO/g9jDtKAJc nbKg== X-Gm-Message-State: AOAM533hKvi4pWi2i8nr9t+ltK4OwXDcIoMfar/HeBwxTzOOAxM5tNjO /1wF5XzGV4RZd6nnqAU4E8XwUWzzxTsHFqUUPITCVg== X-Google-Smtp-Source: ABdhPJyA/zIjInLWcP/GIfBpdeHqyt3GJkS3J7irVtSmj0CTUl2YFN3eeHr7YvBv5Ph96jI/SWrzuLo5P5BSZmIvhnE= X-Received: by 2002:a25:9d86:: with SMTP id v6mr31412357ybp.366.1619523199720; Tue, 27 Apr 2021 04:33:19 -0700 (PDT) MIME-Version: 1.0 References: <20210427102427.11066-1-colin.king@canonical.com> In-Reply-To: <20210427102427.11066-1-colin.king@canonical.com> From: Bartosz Golaszewski Date: Tue, 27 Apr 2021 13:33:09 +0200 Message-ID: Subject: Re: [PATCH][next] gpio: sim: Fix dereference of free'd pointer config To: Colin King Cc: Linus Walleij , Andy Shevchenko , linux-gpio , kernel-janitors@vger.kernel.org, LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 27, 2021 at 12:24 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. > > Addresses-Coverity: ("Read from pointer aftyer free") > Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier") > Signed-off-by: Colin Ian King > --- > drivers/gpio/gpio-sim.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c > index 2e2e6399e453..7bba5783a043 100644 > --- a/drivers/gpio/gpio-sim.c > +++ b/drivers/gpio/gpio-sim.c > @@ -751,8 +751,10 @@ gpio_sim_config_make_item(struct config_group *group, const char *name) > > config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL); > if (config->id < 0) { > + int id = config->id; > + > kfree(config); > - return ERR_PTR(config->id); > + return ERR_PTR(id); > } > > config_item_init_type_name(&config->item, name, > -- > 2.30.2 > Thanks! Can you do something like this: 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; I think this looks more elegant without the local variable inside the if. Bart