From nobody Tue Dec 30 14:48:42 2025 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 5468AC4332F for ; Tue, 14 Nov 2023 19:53:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232272AbjKNTxU (ORCPT ); Tue, 14 Nov 2023 14:53:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229569AbjKNTxS (ORCPT ); Tue, 14 Nov 2023 14:53:18 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FAF1EB for ; Tue, 14 Nov 2023 11:53:14 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 473DBC433C8; Tue, 14 Nov 2023 19:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699991592; bh=p5bXNYWZQPXVZtSAziETIAWqwitA5MwvAafu84FIsRc=; h=Date:From:To:Cc:Subject:From; b=Xu1CUwPsb8NHywQsuf0ZjveiUXv6X56buMrIIKqhntvic2H0v69ZAGSIpnJd4JGXq x62nDwx5EpPDgApZdmHcRyahh3cgVMVMcqSQuN0tHGMd5q9TjcJIwdd/AJWnvOybct BxyPFjHQ59HKLzh3aSNwATPGQCZXSmpoR6nVlFQUmAr7+xOGmRx3sX2RfXekyk5/gt +j28UfzElp+1DtYEdQl6NrFRsLL/3A9eJGxe64yy2d+x6FMpIrgIhI3mVMPK7Dt7jN wbXRG4wrJ9T76vOS1vvmbqI5iODtF/BUyde4KI/XcWhpaW/SpEkp2mTjDlnDjaMqCo VYw7dCdZvPMYQ== Date: Tue, 14 Nov 2023 13:53:08 -0600 From: "Gustavo A. R. Silva" To: Jean Delvare , Guenter Roeck , Joel Stanley , Andrew Jeffery Cc: linux-hwmon@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2][next] hwmon: (aspeed-pwm-tacho) Fix -Wstringop-overflow warning in aspeed_create_fan_tach_channel() Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Based on the documentation below, the maximum number of Fan tach channels is 16: Documentation/devicetree/bindings/hwmon/aspeed-pwm-tacho.txt:45: 45 - aspeed,fan-tach-ch : should specify the Fan tach input channel. 46 integer value in the range 0 through 15, with 0 indicat= ing 47 Fan tach channel 0 and 15 indicating Fan tach channel 1= 5. 48 At least one Fan tach input channel is required. However, the compiler doesn't know that, and legitimaly warns about a poten= tial overwrite in array `u8 fan_tach_ch_source[16]` in `struct aspeed_pwm_tacho_= data`, in case `index` takes a value outside the boundaries of the array: drivers/hwmon/aspeed-pwm-tacho.c: 179 struct aspeed_pwm_tacho_data { ... 184 bool fan_tach_present[16]; ... 193 u8 fan_tach_ch_source[16]; 196 }; In function =E2=80=98aspeed_create_fan_tach_channel=E2=80=99, inlined from =E2=80=98aspeed_create_fan=E2=80=99 at drivers/hwmon/aspee= d-pwm-tacho.c:877:2, inlined from =E2=80=98aspeed_pwm_tacho_probe=E2=80=99 at drivers/hwmon/= aspeed-pwm-tacho.c:936:9: drivers/hwmon/aspeed-pwm-tacho.c:751:49: warning: writing 1 byte into a reg= ion of size 0 [-Wstringop-overflow=3D] 751 | priv->fan_tach_ch_source[index] =3D pwm_source; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~ drivers/hwmon/aspeed-pwm-tacho.c: In function =E2=80=98aspeed_pwm_tacho_pro= be=E2=80=99: drivers/hwmon/aspeed-pwm-tacho.c:193:12: note: at offset [48, 255] into des= tination object =E2=80=98fan_tach_ch_source=E2=80=99 of size 16 193 | u8 fan_tach_ch_source[16]; | ^~~~~~~~~~~~~~~~~~ Fix this by sanity checking `index` before using it to index arrays of size 16 elements in `struct aspeed_pwm_tacho_data`. Also, pass `dev` as argument to function `aspeed_create_fan_tach_channel()`, and add an error message in case `index` is out-of-bounds, in which case return `-EINVAL`. Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook --- Changes in v2: - Pass `dev` to function aspeed_create_fan_tach_channel() and return -EINVAL in case of error. (Guenter) - Update changelog text. v1: - Link: https://lore.kernel.org/linux-hardening/ZVJ7JBFoULzY3VGx@work/ drivers/hwmon/aspeed-pwm-tacho.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-ta= cho.c index 997df4b40509..9a209e064e46 100644 --- a/drivers/hwmon/aspeed-pwm-tacho.c +++ b/drivers/hwmon/aspeed-pwm-tacho.c @@ -166,6 +166,8 @@ =20 #define MAX_CDEV_NAME_LEN 16 =20 +#define MAX_ASPEED_FAN_TACH_CHANNELS 16 + struct aspeed_cooling_device { char name[16]; struct aspeed_pwm_tacho_data *priv; @@ -181,7 +183,7 @@ struct aspeed_pwm_tacho_data { struct reset_control *rst; unsigned long clk_freq; bool pwm_present[8]; - bool fan_tach_present[16]; + bool fan_tach_present[MAX_ASPEED_FAN_TACH_CHANNELS]; u8 type_pwm_clock_unit[3]; u8 type_pwm_clock_division_h[3]; u8 type_pwm_clock_division_l[3]; @@ -190,7 +192,7 @@ struct aspeed_pwm_tacho_data { u16 type_fan_tach_unit[3]; u8 pwm_port_type[8]; u8 pwm_port_fan_ctrl[8]; - u8 fan_tach_ch_source[16]; + u8 fan_tach_ch_source[MAX_ASPEED_FAN_TACH_CHANNELS]; struct aspeed_cooling_device *cdev[8]; const struct attribute_group *groups[3]; }; @@ -737,7 +739,8 @@ static void aspeed_create_pwm_port(struct aspeed_pwm_ta= cho_data *priv, aspeed_set_pwm_port_fan_ctrl(priv, pwm_port, INIT_FAN_CTRL); } =20 -static void aspeed_create_fan_tach_channel(struct aspeed_pwm_tacho_data *p= riv, +static int aspeed_create_fan_tach_channel(struct device *dev, + struct aspeed_pwm_tacho_data *priv, u8 *fan_tach_ch, int count, u8 pwm_source) @@ -746,11 +749,17 @@ static void aspeed_create_fan_tach_channel(struct asp= eed_pwm_tacho_data *priv, =20 for (val =3D 0; val < count; val++) { index =3D fan_tach_ch[val]; + if (index >=3D MAX_ASPEED_FAN_TACH_CHANNELS) { + dev_err(dev, "Invalid Fan Tach input channel %u\n.", index); + return -EINVAL; + } aspeed_set_fan_tach_ch_enable(priv->regmap, index, true); priv->fan_tach_present[index] =3D true; priv->fan_tach_ch_source[index] =3D pwm_source; aspeed_set_fan_tach_ch_source(priv->regmap, index, pwm_source); } + + return 0; } =20 static int @@ -874,7 +883,10 @@ static int aspeed_create_fan(struct device *dev, fan_tach_ch, count); if (ret) return ret; - aspeed_create_fan_tach_channel(priv, fan_tach_ch, count, pwm_port); + + ret =3D aspeed_create_fan_tach_channel(dev, priv, fan_tach_ch, count, pwm= _port); + if (ret) + return ret; =20 return 0; } --=20 2.34.1