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 4ABE4C433EF for ; Mon, 18 Apr 2022 02:20:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235830AbiDRCXR (ORCPT ); Sun, 17 Apr 2022 22:23:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232930AbiDRCXP (ORCPT ); Sun, 17 Apr 2022 22:23:15 -0400 Received: from mail.meizu.com (edge05.meizu.com [157.122.146.251]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F392717E25; Sun, 17 Apr 2022 19:20:36 -0700 (PDT) Received: from IT-EXMB-1-125.meizu.com (172.16.1.125) by mz-mail12.meizu.com (172.16.1.108) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 18 Apr 2022 10:20:37 +0800 Received: from [172.16.137.70] (172.16.137.70) by IT-EXMB-1-125.meizu.com (172.16.1.125) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Mon, 18 Apr 2022 10:20:35 +0800 Message-ID: <3d1b3b5b-6125-f14b-6a0b-85f5c94d6f7a@meizu.com> Date: Mon, 18 Apr 2022 10:20:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH V2] iio: gp2ap020a00f: Fix signedness bug To: Jonathan Cameron CC: Lars-Peter Clausen , , References: <1649985637-18854-1-git-send-email-baihaowen@meizu.com> <20220415185205.26a3d352@jic23-huawei> From: baihaowen In-Reply-To: <20220415185205.26a3d352@jic23-huawei> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [172.16.137.70] X-ClientProxiedBy: IT-EXMB-1-126.meizu.com (172.16.1.126) To IT-EXMB-1-125.meizu.com (172.16.1.125) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 4/16/22 1:52 AM, Jonathan Cameron 写道: > On Fri, 15 Apr 2022 09:20:37 +0800 > Haowen Bai wrote: > >> function gp2ap020a00f_get_thresh_reg() is unsigned but returning -EINVAL >> errcode, and thresh_reg_l is unsigned but receiving -EINVAL errcode. so >> we have to change u8 -> int. >> >> Signed-off-by: Haowen Bai > Hi, > > The return value is not checked in *read_event_val(), so if we actually got > -EINVAL (in reality we can't because the switch in *_get_thresh_reg*) always > matches) then we'd use it to index an array (after performing some maths on > the value). So please also add a check that the return value is not > negative in read_event_val() > > Same is true or write_event_val. > > > Note that the bug here is probably the fact we return -EINVAL in the > first place. We could just stop doing that but it would be non obvious > when looking at the code that we couldn't get a failure to match in > the switch statement - so fixing as you have done (plus the extra > check I'm requesting) is probably the neatest solution. > > Thanks, > > Jonathan > > >> --- >> V1->V2: s8 is not enough to hold an (arbitrary) error code. To be on the safe >> side we need to use int >> >> drivers/iio/light/gp2ap020a00f.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iio/light/gp2ap020a00f.c b/drivers/iio/light/gp2ap020a00f.c >> index b820041159f7..b0e62d3c6fa0 100644 >> --- a/drivers/iio/light/gp2ap020a00f.c >> +++ b/drivers/iio/light/gp2ap020a00f.c >> @@ -994,7 +994,7 @@ static irqreturn_t gp2ap020a00f_trigger_handler(int irq, void *data) >> return IRQ_HANDLED; >> } >> >> -static u8 gp2ap020a00f_get_thresh_reg(const struct iio_chan_spec *chan, >> +static int gp2ap020a00f_get_thresh_reg(const struct iio_chan_spec *chan, >> enum iio_event_direction event_dir) >> { >> switch (chan->type) { >> @@ -1025,7 +1025,7 @@ static int gp2ap020a00f_write_event_val(struct iio_dev *indio_dev, >> struct gp2ap020a00f_data *data = iio_priv(indio_dev); >> bool event_en = false; >> u8 thresh_val_id; >> - u8 thresh_reg_l; >> + int thresh_reg_l; >> int err = 0; >> >> mutex_lock(&data->lock); >> @@ -1082,7 +1082,7 @@ static int gp2ap020a00f_read_event_val(struct iio_dev *indio_dev, >> int *val, int *val2) >> { >> struct gp2ap020a00f_data *data = iio_priv(indio_dev); >> - u8 thresh_reg_l; >> + int thresh_reg_l; >> int err = IIO_VAL_INT; >> >> mutex_lock(&data->lock); hi Jonathan Cameron Thank you for your suggestion. resended :). -- Haowen Bai