CVE-2024-36899

/// Technical description

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

gpiolib: cdev: Fix use after free in lineinfo_changed_notify

The use-after-free issue occurs as follows: when the GPIO chip device file

is being closed by invoking gpio_chrdev_release(), watched_lines is freed

by bitmap_free(), but the unregistration of lineinfo_changed_nb notifier

chain failed due to waiting write rwsem. Additionally, one of the GPIO

chip's lines is also in the release process and holds the notifier chain's

read rwsem. Consequently, a race condition leads to the use-after-free of

watched_lines.

Here is the typical stack when issue happened:

[free]

gpio_chrdev_release()

--> bitmap_free(cdev->watched_lines) <-- freed

--> blocking_notifier_chain_unregister()

--> down_write(&nh->rwsem) <-- waiting rwsem

--> __down_write_common()

--> rwsem_down_write_slowpath()

--> schedule_preempt_disabled()

-

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References