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CVE-2024-36899NVD status: Modified

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2024-36899 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.0 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 2dfbb920a89bdc58087672ad5325dc6c588b6860, 2d008d4961b039d2edce8976289773961b7e5fb5, d38c49f7bdf14381270736299e2ff68ec248a017 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 2dfbb920a89bdc58087672ad5325dc6c588b6860 or 2d008d4961b039d2edce8976289773961b7e5fb5 or d38c49f7bdf14381270736299e2ff68ec248a017 or 95ca7c90eaf5ea8a8460536535101e3e81160e2a, whichever matches your release line, or a later version.
  2. Update SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to V1.1.1 or a later version.
  3. Update Linux Kernel to 6.6.31 or 6.8.10, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, 2dfbb920a89bdc58087672ad5325dc6c588b6860; 51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, 2d008d4961b039d2edce8976289773961b7e5fb5; 51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, d38c49f7bdf14381270736299e2ff68ec248a017; 51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, 95ca7c90eaf5ea8a8460536535101e3e81160e2a; 51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, ca710b5f40b8b16fdcad50bebd47f50e4c62d239; 51c1064e82e77b39a49889287ca50709303e2f26 up to, but not including, 02f6b0e1ec7e0e7d059dddc893645816552039da; 5.72dfbb920a89bdc58087672ad5325dc6c588b6860, 2d008d4961b039d2edce8976289773961b7e5fb5, d38c49f7bdf14381270736299e2ff68ec248a017, 95ca7c90eaf5ea8a8460536535101e3e81160e2a, ca710b5f40b8b16fdcad50bebd47f50e4c62d239, 02f6b0e1ec7e0e7d059dddc893645816552039da
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystembefore V1.1.1V1.1.1
LinuxLinux Kernel5.7 up to, but not including, 6.6.31; 6.7 up to, but not including, 6.8.10; 6.96.6.31, 6.8.10

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official 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() --> 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

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