Use After Free Affecting linux-6.1 package, versions <6.1.119-1~deb11u1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.04% (5th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-8601178
  • published2 Jan 2025
  • disclosed12 Jul 2024

Introduced: 12 Jul 2024

CVE-2024-39495  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.119-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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

greybus: Fix use-after-free bug in gb_interface_release due to race condition.

In gb_interface_create, &intf->mode_switch_completion is bound with gb_interface_mode_switch_work. Then it will be started by gb_interface_request_mode_switch. Here is the relevant code. if (!queue_work(system_long_wq, &intf->mode_switch_work)) { ... }

If we call gb_interface_release to make cleanup, there may be an unfinished work. This function will call kfree to free the object "intf". However, if gb_interface_mode_switch_work is scheduled to run after kfree, it may cause use-after-free error as gb_interface_mode_switch_work will use the object "intf". The possible execution flow that may lead to the issue is as follows:

CPU0 CPU1

                        |   gb_interface_create
                        |   gb_interface_request_mode_switch

gb_interface_release | kfree(intf) (free) | | gb_interface_mode_switch_work | mutex_lock(&intf->mutex) (use)

Fix it by canceling the work before kfree.

CVSS Scores

version 3.1