Access of Resource Using Incompatible Type ('Type Confusion') Affecting kernel-rt-64k-modules package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-modules package and not the kernel-rt-64k-modules package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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.

• https://bugzilla.redhat.com/show_bug.cgi?id=2521404
• https://access.redhat.com/security/cve/CVE-2026-74711
• https://git.kernel.org/stable/c/0b121de89a99c54bcf516999b04e8531c84f08d5
• https://git.kernel.org/stable/c/59bd68ab05a8f9c9a60b6ec44682084184803ff4
• https://git.kernel.org/stable/c/821f6416e69782fa662aff94b5ea52c943042790