Linux Kernel up to 6.6.50/6.10.9 fscache timer_reduce use after free

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.6.50/6.10.9. The impacted element is the function timer_reduce of the component fscache. The manipulation results in use after free. This vulnerability is cataloged as CVE-2024-46786. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.50/6.10.9. It has been classified as critical. Affected is the function timer_reduce of the component fscache. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: fscache: delete fscache_cookie_lru_timer when fscache exits to avoid UAF The fscache_cookie_lru_timer is initialized when the fscache module is inserted, but is not deleted when the fscache module is removed. If timer_reduce() is called before removing the fscache module, the fscache_cookie_lru_timer will be added to the timer list of the current cpu. Afterwards, a use-after-free will be triggered in the softIRQ after removing the fscache module, as follows: ================================================================== BUG: unable to handle page fault for address: fffffbfff803c9e9 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 21ffea067 P4D 21ffea067 PUD 21ffe6067 PMD 110a7c067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G W 6.11.0-rc3 #855 Tainted: [W]=WARN RIP: 0010:__run_timer_base.part.0+0x254/0x8a0 Call Trace: <IRQ> tmigr_handle_remote_up+0x627/0x810 __walk_groups.isra.0+0x47/0x140 tmigr_handle_remote+0x1fa/0x2f0 handle_softirqs+0x180/0x590 irq_exit_rcu+0x84/0xb0 sysvec_apic_timer_interrupt+0x6e/0x90 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:default_idle+0xf/0x20 default_idle_call+0x38/0x60 do_idle+0x2b5/0x300 cpu_startup_entry+0x54/0x60 start_secondary+0x20d/0x280 common_startup_64+0x13e/0x148 </TASK> Modules linked in: [last unloaded: netfs] ================================================================== Therefore delete fscache_cookie_lru_timer when removing the fscahe module.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2024-46786 since 09/11/2024. The exploitability is told to be difficult. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 04/06/2026).

The vulnerability scanner Nessus provides a plugin with the ID 211516 (CentOS 9 : kernel-5.14.0-529.el9), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.51 or 6.10.10 eliminates this vulnerability. Applying the patch e0d724932ad1/0a11262549ac/72a6e22c604c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (211516) and CERT Bund (WID-SEC-2024-2173). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Debian Linux
• Google Cloud Platform
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• IBM InfoSphere Guardium
• Oracle Linux
• RESF Rocky Linux
• Open Source Linux Kernel
• SolarWinds Security Event Manager

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.6.50
• 6.10.0
• 6.10.1
• 6.10.2
• 6.10.3
• 6.10.4
• 6.10.5
• 6.10.6
• 6.10.7
• 6.10.8
• 6.10.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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