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Wong" , "Mark M. Hoffman" , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, sashiko-bot@kernel.org Subject: Re: [hwmon PATCH v2 3/8] hwmon: (adt7470) Fix busy-loop and I2C flooding in update thread Message-ID: References: <20260727-adt7470_fixes-v2-0-598e38a46ba6@gmail.com> <20260727-adt7470_fixes-v2-3-598e38a46ba6@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260727-adt7470_fixes-v2-3-598e38a46ba6@gmail.com> On Mon, Jul 27, 2026 at 09:22:19PM -0300, Luiz Angelo Daros de Luca wrote: > When userspace configures 'auto_update_interval' to 0 via sysfs, the > background kthread executes schedule_timeout_interruptible(0), which > returns immediately. > > If 'num_temp_sensors' is concurrently or previously set to 0, the > msleep_interruptible() delay inside adt7470_read_temperatures() also > becomes 0. This combination forces the background thread into a tight, > unbounded busy-loop, hogging the CPU and flooding the I2C bus with a > continuous stream of transactions. > > Fix this vulnerability by raising the lower limit of the clamp_val in > auto_update_interval_store() from 0 to 500 milliseconds. This guarantees > a reasonable minimum sleep window between sensor updates, protecting the > system from intentional or accidental I2C bus denial of service. > > Reported-by: sashiko-bot@kernel.org > Closes: https://lore.kernel.org/r/20260716213252.EACA71F000E9@smtp.kernel.org > Fixes: 89fac11cb3e7 ("adt7470: make automatic fan control really work") > Signed-off-by: Luiz Angelo Daros de Luca Applied. Thanks, Guenter