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() --> schedule() [use] st54spi_gpio_dev_release() --> gpio_free() --> gpiod_free() --> gpiod_free_commit() --> gpiod_line_state_notify() --> blocking_notifier_call_chain() --> down_read(&nh->rwsem); <-- held rwsem --> notifier_call_chain() --> lineinfo_changed_notify() --> test_bit(xxxx, cdev->watched_lines) <-- use after free The side effect of the use-after-free issue is that a GPIO line event is being generated for userspace where it shouldn't. However, since the chrdev is being closed, userspace won't have the chance to read that event anyway. To fix the issue, call the bitmap_free() function after the unregistration of lineinfo_changed_nb notifier chain.
History

Tue, 24 Sep 2024 11:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/a:redhat:rhel_eus:9.2
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat enterprise Linux

Tue, 24 Sep 2024 06:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.2::nfv
Vendors & Products Redhat
Redhat rhel Eus

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-05-30T15:29:02.591Z

Updated: 2024-11-05T09:27:43.825Z

Reserved: 2024-05-30T15:25:07.066Z

Link: CVE-2024-36899

cve-icon Vulnrichment

Updated: 2024-08-02T03:43:50.054Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-05-30T16:15:13.510

Modified: 2024-05-30T18:18:58.870

Link: CVE-2024-36899

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-05-30T00:00:00Z

Links: CVE-2024-36899 - Bugzilla