From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Date: Sun, 22 May 2022 11:07:52 +0200 Subject: [Ksummit-discuss] uninitialized variables bugs In-Reply-To: <20220506091338.GE4031@kadam> References: <20220506091338.GE4031@kadam> Message-ID: On 06/05/2022 11:13, Dan Carpenter wrote: > There is also stuff like this which is harmless: > > uint val; > > ret = read(&val); > *p = val; // <-- uninitialized variable if read() fails > return ret; > > Btw, here is how to run Smatch on your code: > https://staticthinking.wordpress.com/2022/04/25/how-to-run-smatch-on-your-code/ In the topic of suppressing false positives we also have several "fixes", sometimes pointed out incorrectly by Coverity, for missing check for of_device_get_match_data(). Compare: https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-aspeed.c#L415 https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-oxnas.c#L216 Although in theory the of_device_get_match_data() can return NULL, in practice it is not possible because driver matches via OF thus there will be always of_device_id->driver data. Coverity screams about it, people fix it by adding checks for NULL, which is pointless. Half of drivers add the !NULL check, half do not... Best regards, Krzysztof 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 D81C2C433F5 for ; Sun, 22 May 2022 09:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242785AbiEVJIQ (ORCPT ); Sun, 22 May 2022 05:08:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240935AbiEVJIN (ORCPT ); Sun, 22 May 2022 05:08:13 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8C18344EB for ; Sun, 22 May 2022 02:07:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5693DB80ACC for ; Sun, 22 May 2022 09:07:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 52A0EC385AA; Sun, 22 May 2022 09:07:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653210476; bh=Tnd9k7iRjgfdcQgXzfq2JZ4qYtO5XwbTFBmo19t2jIA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=S8xXimqwBxzn98bU6z1yaq8fOwEkP+dYMHN4eCURaFRz1fCsgAvfxI9/nsO9Umk+2 SA1sZoI38b6YE61f3Lya/sy7xMavAKqSUYWRuKg3zXQwN9jIf337VBGkqckkyI6Yco gFjd7P1zz1tNPnfmBUGwqel+eI3I5ACsqtRgOrSnpcMl2Jdjh7+joPY4TioEsLFQ// i8+ZpTnOSrNQWUuShcWtDsJuzaS41D/07R1BjG1RnAXK/cpBCEnrasRXZqNAi4iMpU 8ZNZzzXyYbLAEbPAbWYRW0XdJWbCqEIedtT3HnQ4A7UsGV2LLJGCTYJiF4ZSTiQc0a NdZYWnmCuBQjQ== Message-ID: Date: Sun, 22 May 2022 11:07:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [Ksummit-discuss] uninitialized variables bugs Content-Language: en-US To: Dan Carpenter , ksummit-discuss@lists.linuxfoundation.org, linux-kernel@vger.kernel.org Cc: Nathan Chancellor , kbuild@lists.01.org, lkp@intel.com References: <20220506091338.GE4031@kadam> From: Krzysztof Kozlowski In-Reply-To: <20220506091338.GE4031@kadam> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/05/2022 11:13, Dan Carpenter wrote: > There is also stuff like this which is harmless: > > uint val; > > ret = read(&val); > *p = val; // <-- uninitialized variable if read() fails > return ret; > > Btw, here is how to run Smatch on your code: > https://staticthinking.wordpress.com/2022/04/25/how-to-run-smatch-on-your-code/ In the topic of suppressing false positives we also have several "fixes", sometimes pointed out incorrectly by Coverity, for missing check for of_device_get_match_data(). Compare: https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-aspeed.c#L415 https://elixir.bootlin.com/linux/v5.18-rc7/source/drivers/clk/clk-oxnas.c#L216 Although in theory the of_device_get_match_data() can return NULL, in practice it is not possible because driver matches via OF thus there will be always of_device_id->driver data. Coverity screams about it, people fix it by adding checks for NULL, which is pointless. Half of drivers add the !NULL check, half do not... Best regards, Krzysztof