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 2A0352DC783; Mon, 17 Aug 2026 14:36:34 +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=1786977396; cv=none; b=BuRKmD+I31xwUbc2yNYiHkpAcF8bTtENzYPNGSu8hnwy8udgkJNexNBDfRyLB1vjaaAUldn2PzaYQetQqSvx8tWCVDy5OMOvAbbeItjfOjWqNUzgIgzKK5h7OX2PuhTQjOfroxGNT8NRyLV9yRUQC4GG00b9WlIQQB8SzvKjnNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786977396; c=relaxed/simple; bh=G2Id+jUO5AEz7kmOE2mlNUrRiooNDQbFgfHB/GQHJXU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QsjZxORxOGfLHHtvtWlo8I9UK3kdJ/d/ceN7au949QYf/wEC498ijSFGzzs7DS1XiE3TDsC5aniHhae5MMdztlii4L7gkMuuQWDVc2E+oEq9y6MF8fGBBirspaooWZP457d804T2OROjHqgH/87pfC+a1smMLg7WiEgRTVP+RP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h81ntuS6; 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="h81ntuS6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 359C51F000E9; Mon, 17 Aug 2026 14:36:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786977394; bh=cfa8Fp4X4E5dLd+DTIjCrr5zOD8Y+39OiR43z/eJ3Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=h81ntuS620cxLBDu5SMe124rHo2ylX2wbAr0dzrqpmlvYJxXqT+3OfMaOWev17k8w oPpznF8uQwV2GzD5OADpVtkfBb0msGO45A/oIWvqSzU+h/JTYXaJccEO9nV8E4jpT0 najR0C4CV1mwTxTFSVg8pOm8SOdcY1+E0FcCaEfM= 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 5.15 274/456] hwmon: (adt7470) Fix divide-by-zero TOCTOU crash in fan speed read Date: Mon, 17 Aug 2026 15:31:04 +0200 Message-ID: <20260817132550.687461444@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132539.792407575@linuxfoundation.org> References: <20260817132539.792407575@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 5.15-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 3fcc10d0d3639..394f0aba3493a 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