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 AA7613DB964; Mon, 17 Aug 2026 13:54:16 +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=1786974859; cv=none; b=trDMb2EaKi1HgbZqWJ6fig2Epzt0HLJ5jJglWMLuQ/vysiKMSAdvFxUmU4qq3qOByRIPX4evT4bel/tSjNV6h7MDdb7Lv5pxt20rWp/pQUkNpFuwNOL95K6ikSMDvFLtNTC0W5RWi0ZhahIT8pLEeFH2YGMnpkCVCL03GmAf5/U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786974859; c=relaxed/simple; bh=n+3zdYHSwHYyCjwMzIcBx4IevyubrY1v9OaOZY07nZ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hFrgT4jxXxzkK8/zV27m4Npjy5tDiZVZkMEUW28LWg1BLxP1R/oiPYBh9NI+0m2WVkastZxykIr87YSQjNxjzvueLWksZk5szYr7bt+cfmG7qoGxtyI8PqEknEEKT0uCrVUZWvqDUXQmzXVomIVQj0oaRpQY/yEvPFuvobQBP+Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=orIPYOwZ; 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="orIPYOwZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B303F1F00A3D; Mon, 17 Aug 2026 13:54:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786974856; bh=SPCAofkezkIm3/vguRCYQNthSTNy+Vev0e1sNA49vWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=orIPYOwZawo0Vx8va8HzIbkOWIpjl2nuURGbS1Iriiu0xsUBo/ezwgadMPl5WATOq tpznQHNxAR/etUuDokigRyi1fkbwaxUuHtsIhCKGgkred6M1gPyCmxTLS2lFTnRPbB n1c/mfN3unETR60PmRw0edUvUPbJJdh5C+pJKi58= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Guenter Roeck , Sasha Levin Subject: [PATCH 6.18 079/250] hwmon: (pmbus/lm25066) Fix PMBus coefficient calculations Date: Mon, 17 Aug 2026 15:30:40 +0200 Message-ID: <20260817132539.672477858@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.466235697@linuxfoundation.org> References: <20260817132536.466235697@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Guenter Roeck [ Upstream commit 0dabe8a56f772f0ece46d2597799f412c277d874 ] In lm25066_probe(), the PMBus coefficients for current and power are scaled based on the shunt resistor value. The calculation evaluates the multiplication using 32-bit arithmetic because info->m is an int and shunt is a u32: static int lm25066_probe(struct i2c_client *client) { ... info->m[PSC_CURRENT_IN] = info->m[PSC_CURRENT_IN] * shunt / 1000; info->m[PSC_POWER] = info->m[PSC_POWER] * shunt / 1000; ... } For large coefficients like 26882 (LM25056) or 15076 (LM5066i), a device tree shunt-resistor-micro-ohms value exceeding approximately 159,000 (159 mOhm, which is physically valid for low-current applications) causes the intermediate product to exceed UINT_MAX (4,294,967,295). This results in a silent wraparound before the division by 1000. Furthermore, if the wrapped value has the most significant bit set, converting it back to the signed int info->m results in negative coefficients. This logic error leads to drastically corrupted current and power readings, which can cause erratic thermal or power management behavior in the system. Fix the problem by using 64-bit operations for the multiply/divide operations. This can still overflow, but only for unreasonably large shunt resistor values. Reported-by: Sashiko Fixes: 94ee5fcc240fe ("hwmon: (pmbus/lm25066) Support configurable sense resistor values") Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/pmbus/lm25066.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/pmbus/lm25066.c b/drivers/hwmon/pmbus/lm25066.c index dd7275a67a0ab..7774d678022e2 100644 --- a/drivers/hwmon/pmbus/lm25066.c +++ b/drivers/hwmon/pmbus/lm25066.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include "pmbus.h" @@ -540,8 +541,8 @@ static int lm25066_probe(struct i2c_client *client) if (of_property_read_u32(client->dev.of_node, "shunt-resistor-micro-ohms", &shunt)) shunt = 1000; - info->m[PSC_CURRENT_IN] = info->m[PSC_CURRENT_IN] * shunt / 1000; - info->m[PSC_POWER] = info->m[PSC_POWER] * shunt / 1000; + info->m[PSC_CURRENT_IN] = DIV_ROUND_CLOSEST_ULL((u64)info->m[PSC_CURRENT_IN] * shunt, 1000); + info->m[PSC_POWER] = DIV_ROUND_CLOSEST_ULL((u64)info->m[PSC_POWER] * shunt, 1000); #if IS_ENABLED(CONFIG_SENSORS_LM25066_REGULATOR) /* LM25056 doesn't support OPERATION */ -- 2.53.0