CVE-2026-98200

Summary

In the Linux kernel, the following vulnerability has been resolved:

hwmon: (hp-wmi-sensors) Fix use-after-free in fungible_show()

nsensor->current_state is dynamically replaced as the sensor's state changes. update_numeric_sensor_from_wobj() does this by freeing the old string and installing a new one:

if (strcmp(trimmed, nsensor->current_state)) {
	new_string = hp_wmi_strdup(dev, trimmed);
	if (new_string) {
		devm_kfree(dev, nsensor->current_state);
		nsensor->current_state = new_string;
	}
}

This function is only ever called from hp_wmi_update_info() while state->lock is held, so the free-and-replace itself is properly serialized against concurrent updates.

fungible_show(), however, reads the same pointer after the lock has already been dropped:

err = hp_wmi_update_info(state, info);
if (err)
	return err;

switch (prop) {
...
case HP_WMI_PROPERTY_CURRENT_STATE:
	seq_printf(seqf, "%s\n", nsensor->current_state);
	break;

hp_wmi_update_info() takes state->lock internally and releases it before returning, so by the time fungible_show() dereferences nsensor->current_state in seq_printf(), no lock is held. Two processes reading a sensor's current_state debugfs entry at overlapping times (or one reading it while another read of the same sensor triggers a refresh) can race: one thread's seq_printf() can be part-way through printing the string at the moment another thread's call into update_numeric_sensor_from_wobj() frees it with devm_kfree() and installs a new pointer, causing a use-after-free read.

Take state->lock around the read in fungible_show() as well, so it can never run concurrently with the free-and-replace in update_numeric_sensor_from_wobj().

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/b6b2a638aa36c441b2c8d0b6bd8ed2bb9701e795
• https://git.kernel.org/stable/c/f59ecfd2c58bace39538f3fff7f43788b3fdb539
• https://git.kernel.org/stable/c/72c85149794a1ccf8d718ffed1521106b5d31968
• https://git.kernel.org/stable/c/9c1e65bc79ff104914b11e6ad972139296ec86fe
• https://git.kernel.org/stable/c/e6cb0b4d4ecb8e71fd2200d907ab2e9663356f69

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