CVE-2024-36899 Affecting kernel-livepatch-5_14_21-150400_24_119-default package, versions <6-150400.9.6.1


Severity

Recommended
medium

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-SLES154-KERNELLIVEPATCH5142115040024119DEFAULT-8225102
  • published17 Oct 2024
  • disclosed16 Oct 2024

Introduced: 16 Oct 2024

CVE-2024-36899  (opens in a new tab)

How to fix?

Upgrade SLES:15.4 kernel-livepatch-5_14_21-150400_24_119-default to version 6-150400.9.6.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-livepatch-5_14_21-150400_24_119-default package and not the kernel-livepatch-5_14_21-150400_24_119-default package as distributed by SLES. See How to fix? for SLES:15.4 relevant fixed versions and status.

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.

CVSS Scores

version 3.1