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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4983585c5c4sm3359512f8f.17.2026.11.10.01.36.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 01:36:14 -0800 (PST) Date: Tue, 10 Nov 2026 09:36:13 +0000 From: David Laight To: Zhu Jun Cc: linux@roeck-us.net, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] hwmon: (w83l786ng) Clamp voltage limits before rounding Message-ID: <20261110093613.52ed3861@pumpkin> In-Reply-To: <20261109101916.17352-1-zhujun2@cmss.chinamobile.com> References: <20261109101916.17352-1-zhujun2@cmss.chinamobile.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 9 Nov 2026 18:19:16 +0800 Zhu Jun wrote: > IN_TO_REG() adds 4 to an unrestricted unsigned long. Inputs close to > ULONG_MAX wrap, so an excessive voltage limit can select register zero > instead of 255. I looked, it really doesn't matter. The 'unrestricted unsigned long' comes from a write to a sysfs value. Nothing will write a value that large unless they are trying to break something, and they can just as well write "0". David > > Clamp to the 0..2040 mV register range before rounding to 8 mV units. > > Fixes: 85f03bccd6e0 ("hwmon: Add support for Winbond W83L786NG/NR") > --- > Validation: x86-64 and i386 driver objects built with W=1. > Source-extracted boundary tests passed on both word sizes; > the corresponding test fails on the base revision. I/O is mocked. > No physical sensor or booted-kernel testing was available. > OpenAI Codex assisted analysis, code, tests and changelog drafting. > Please review and add your own Signed-off-by before submitting. > > drivers/hwmon/w83l786ng.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/hwmon/w83l786ng.c b/drivers/hwmon/w83l786ng.c > index d16afda34e41..0cd545011e73 100644 > --- a/drivers/hwmon/w83l786ng.c > +++ b/drivers/hwmon/w83l786ng.c > @@ -101,7 +101,7 @@ static int temp_from_reg(int val) > * in mV as would be measured on the chip input pin, need to just > * multiply/divide by 8 to translate from/to register values. > */ > -#define IN_TO_REG(val) (clamp_val((((val) + 4) / 8), 0, 255)) > +#define IN_TO_REG(val) ((clamp_val((val), 0, 2040) + 4) / 8) > #define IN_FROM_REG(val) ((val) * 8) > > #define DIV_FROM_REG(val) (1 << (val)) > > base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb