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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11E54C433EF for ; Thu, 18 Nov 2021 16:04:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F2EF561423 for ; Thu, 18 Nov 2021 16:04:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232799AbhKRQHG (ORCPT ); Thu, 18 Nov 2021 11:07:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:44332 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229936AbhKRQHG (ORCPT ); Thu, 18 Nov 2021 11:07:06 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1BD2B613A3; Thu, 18 Nov 2021 16:04:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637251445; bh=oa7oSmJxHRoFc+bzoJMwa3+/zIjqvCBcVLfQMRXh6d4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cepdl9GxzCeJczoIb9omidGHLGmWsBUuiq31lUe/OvdnSh1CiOuhPyx/W6S+8szGJ ZrCUzLyrcCNXtlhzWndtlnFyDq9nEmdztk2YN1fdtJuDzG12UU/W1PpVHP1cTYIgs+ InUTz28W7wy7dd9i7Zc/v7eQu+kIAozGh+mqyTFT12aEZpH+U9mbBg0TPd9Fcr4SSK z8sPG4htZ+grxKcOMVB6OtNUd43RKijEBU/oHsz9cBsDVHAjoS9ClDOdqCcKWBKoEG 8MMWvB+K2MhSwiRsKtMnsafQQlm7f1iDRM9sfCj5hFgmEryQcpo37BYfP7PRVaAfo6 aYD6dXP1Jeq4A== Date: Thu, 18 Nov 2021 09:03:59 -0700 From: Nathan Chancellor To: Arnd Bergmann Cc: Luca Coelho , Kalle Valo , Arnd Bergmann , kernel test robot , Nick Desaulniers , "David S. Miller" , Jakub Kicinski , Johannes Berg , Yaara Baruch , Matti Gottlieb , Emmanuel Grumbach , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH] [v3] iwlwifi: pcie: fix constant-conversion warning Message-ID: References: <20211118142124.526901-1-arnd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211118142124.526901-1-arnd@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thu, Nov 18, 2021 at 03:21:02PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > gcc-11 points out a potential issue with integer overflow when > the iwl_dev_info_table[] array is empty: > > drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion] > for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) { > ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~ For what it's worth, I do see this warning with Clang when both CONFIG_IWLDVM and CONFIG_IWLMVM are disabled and looking through the GCC warning docs [1], I do not see a -Wconstant-conversion option? Maybe there is another warning that is similar but that warning right there appears to have come from clang, as it matches mine exactly. drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion] for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) { ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~ 1 error generated. [1]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html > This is still harmless, as the loop correctly terminates, but adding > an extra range check makes that obvious to both readers and to the > compiler. > > Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()") > Reported-by: kernel test robot > Cc: Nick Desaulniers > Signed-off-by: Arnd Bergmann Regardless of above, this resolves the warning for clang. Reviewed-by: Nathan Chancellor > --- > Changes in v3: > - make it actually work with gcc-11 > - fix commit message s/clang/gcc-11/ > > Changes in v2: > - replace int cast with a range check > --- > drivers/net/wireless/intel/iwlwifi/pcie/drv.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c > index c574f041f096..395e328c6a07 100644 > --- a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c > +++ b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c > @@ -1339,9 +1339,13 @@ iwl_pci_find_dev_info(u16 device, u16 subsystem_device, > u16 mac_type, u8 mac_step, > u16 rf_type, u8 cdb, u8 rf_id, u8 no_160, u8 cores) > { > + int num_devices = ARRAY_SIZE(iwl_dev_info_table); > int i; > > - for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) { > + if (!num_devices) > + return NULL; > + > + for (i = num_devices - 1; i >= 0; i--) { > const struct iwl_dev_info *dev_info = &iwl_dev_info_table[i]; > > if (dev_info->device != (u16)IWL_CFG_ANY && > -- > 2.29.2 >