From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB44527466A; Fri, 7 Aug 2026 15:19:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786115944; cv=none; b=JAhLVo3TT6QM0vvDdGA8aZTutZ6NjTU17KSenkZAg8NUWDPZna8jK47jA/odZf6hidUVG3y0J8YzAsKP5MCDFRRq3JuKcL1Adna+O4wfsUNubpSryM72M12qS1XZGhYOV5ioXLM+KBXQ25No606h+gSuoL93X6arM9/iwqfCyto= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786115944; c=relaxed/simple; bh=T3grok1/WSle8wHn8wAlWEpgDGl/OTJzdp5COj2GWjA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OKR2Wc4K2T/5icaB7HcZ4zhdrlYfMZXAu+4Q2h1ajPNqZps5XJPMLAfG/yhDlpRNyirK9bbnHtGoUqtG64ZKNvQyOTxHToeuM8vO5UC6V6W1OvAKlDOibITItu5s87ds4mwfWJ9kaMUVylvfNfhdkub4j+VxT1JirBsrhMHKIfU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gY8HAZj0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gY8HAZj0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F41121F00A3D; Fri, 7 Aug 2026 15:19:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786115943; bh=V7xXPRO/mRfPWjEWkmQSEZ0v5l7Sgf6T3/VmkwpR058=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gY8HAZj0BT0KRzu8tm/BSZbm+TaPPkQtDMfX5nQdmDMsqel+/JF+EIRz4+JdCfW5T eSOId2lDH7bokyc74U7CcEmqAR4F3idzPetT05oS42CPLhQnhIHMeHFDZ3NNQtCPds N1WboEvhW7o9Bq0tKZDQHeokP8uWKBoYlX1MaH6o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot@kernel.org, Luiz Angelo Daros de Luca , Guenter Roeck , Sasha Levin Subject: [PATCH 6.6 056/261] hwmon: (adt7470) Fix divide-by-zero TOCTOU crash in fan speed read Date: Fri, 7 Aug 2026 16:36:53 +0200 Message-ID: <20260807143416.594463699@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143415.358597922@linuxfoundation.org> References: <20260807143415.358597922@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luiz Angelo Daros de Luca [ Upstream commit 1b46fe9dc8f8de59310f37e6c5e5c0e05ded46c3 ] If the fan data becomes 0 between the FAN_DATA_VALID() check and the FAN_PERIOD_TO_RPM() conversion, it will result in a divide-by-zero crash due to a race with a concurrent update of the cached fan value. Fix a TOCTOU issue by reading fan data once. Reported-by: sashiko-bot@kernel.org Closes: https://lore.kernel.org/r/20260727034929.E29B71F000E9@smtp.kernel.org/ Fixes: fc958a61ff6d ("hwmon: (adt7470) Convert to devm_hwmon_device_register_with_info API") Signed-off-by: Luiz Angelo Daros de Luca Link: https://lore.kernel.org/r/20260727-adt7470_fixes-v2-7-598e38a46ba6@gmail.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/adt7470.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c index 0ec0f1e4dcbc9..7b9cb44749d95 100644 --- a/drivers/hwmon/adt7470.c +++ b/drivers/hwmon/adt7470.c @@ -660,36 +660,33 @@ static ssize_t alarm_mask_store(struct device *dev, static int adt7470_fan_read(struct device *dev, u32 attr, int channel, long *val) { struct adt7470_data *data = adt7470_update_device(dev); + u16 fan_data; if (IS_ERR(data)) return PTR_ERR(data); switch (attr) { case hwmon_fan_input: - if (FAN_DATA_VALID(data->fan[channel])) - *val = FAN_PERIOD_TO_RPM(data->fan[channel]); - else - *val = 0; + fan_data = READ_ONCE(data->fan[channel]); break; case hwmon_fan_min: - if (FAN_DATA_VALID(data->fan_min[channel])) - *val = FAN_PERIOD_TO_RPM(data->fan_min[channel]); - else - *val = 0; + fan_data = READ_ONCE(data->fan_min[channel]); break; case hwmon_fan_max: - if (FAN_DATA_VALID(data->fan_max[channel])) - *val = FAN_PERIOD_TO_RPM(data->fan_max[channel]); - else - *val = 0; + fan_data = READ_ONCE(data->fan_max[channel]); break; case hwmon_fan_alarm: *val = !!(data->alarm & FAN_ALARM_BIT(channel)); - break; + return 0; default: return -EOPNOTSUPP; } + if (FAN_DATA_VALID(fan_data)) + *val = FAN_PERIOD_TO_RPM(fan_data); + else + *val = 0; + return 0; } -- 2.53.0