CVE-2026-74711hwmon: (pmbus) Fix type confusion in notification logic

Official description

In the Linux kernel, the following vulnerability has been resolved: hwmon: (pmbus) Fix type confusion in notification logic Sashiko reports: At the start of the loop in pmbus_notify(), the code unconditionally casts every attribute to a struct sensor_device_attribute: drivers/hwmon/pmbus/pmbus_core.c:pmbus_notify() { for (i = 0; i < data->num_attributes; i++) { struct device_attribute *da = to_dev_attr(data->group.attrs[i]); struct sensor_device_attribute *attr = to_sensor_dev_attr(da); int index = attr->index; ... } However, data->group.attrs can contain other types like struct pmbus_samples_reg or struct pmbus_sensor, which only embed a base struct device_attribute. If da is a struct pmbus_samples_reg, dev_attr is the last member. Casting it to struct sensor_device_attribute and reading the index field appears to access memory past the end of the allocation, which might trigger a slab-out-of-bounds read. Additionally, if da is a struct pmbus_sensor, casting it causes the index field to overlap with the page, phase, and reg fields. Could this produce a garbage mask on little-endian systems that spuriously matches the target reg, page, and flags during an alert? Fix the problem by using struct sensor_device_attr in struct pmbus_sensor and struct pmbus_label. Since those attributes never trigger a notification, set the value of attr->index to -1 for them. Use this value to distinguish from boolean attributes which _can_ trigger a notification and use the index field to encode mask, page, and register values.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/ce443f6827b97e03a0fb34ebfddc8939c85e0500
• https://git.kernel.org/stable/c/1c8dd39d48494cceb2c27c1911cbf26d10ce8514
• https://git.kernel.org/stable/c/821f6416e69782fa662aff94b5ea52c943042790
• https://git.kernel.org/stable/c/0b121de89a99c54bcf516999b04e8531c84f08d5
• https://git.kernel.org/stable/c/59bd68ab05a8f9c9a60b6ec44682084184803ff4