Linux Kernel hwmon pmbus: Type Confusion in notify logic
CVE-2026-74711 Published on August 22, 2026
hwmon: (pmbus) Fix type confusion in notification logic
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.
Products Associated with CVE-2026-74711
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Affected Versions
Linux:- Version f469bde9afd136598a0c4edc054296e6046f90ee and below 821f6416e69782fa662aff94b5ea52c943042790 is affected.
- Version f469bde9afd136598a0c4edc054296e6046f90ee and below 0b121de89a99c54bcf516999b04e8531c84f08d5 is affected.
- Version f469bde9afd136598a0c4edc054296e6046f90ee and below 59bd68ab05a8f9c9a60b6ec44682084184803ff4 is affected.
- Version 6.4 is affected.
- Before 6.4 is unaffected.
- Version 6.18.45, <= 6.18.* is unaffected.
- Version 7.1.9, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.