In the Linux kernel, the following vulnerability has been resolved:
hwmon: (adt7470) Fix busy-loop and I2C flooding in update thread
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.
References
- https://git.kernel.org/stable/c/1a42bd72a66205e439db1d1142442b62d393408a
- https://git.kernel.org/stable/c/38e6b5ce5794ff09442231cc171c2be5e900bab3
- https://git.kernel.org/stable/c/5ea299c3aa42a827f6a863eeead6de3525bbb17a
- https://git.kernel.org/stable/c/82d65f7ef11edcea0228745440b8b4b1f222c34c
- https://git.kernel.org/stable/c/cb0b7f9c43b0abbd422a7e4c2c85e91db429207c