Linux Kernel up to 6.19.9/7.0-rc4 arm_mpam mpam_restore_mbwu_state null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.19.9/7.0-rc4. It has been declared as critical. This vulnerability affects the function mpam_restore_mbwu_state of the component arm_mpam. The manipulation results in null pointer dereference. This vulnerability is identified as CVE-2026-23433. The attack is only possible with local access. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.19.9/7.0-rc4. Affected is the function mpam_restore_mbwu_state of the component arm_mpam. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: arm_mpam: Fix null pointer dereference when restoring bandwidth counters When an MSC supporting memory bandwidth monitoring is brought offline and then online, mpam_restore_mbwu_state() calls __ris_msmon_read() via ipi to restore the configuration of the bandwidth counters. It doesn't care about the value read, mbwu_arg.val, and doesn't set it leading to a null pointer dereference when __ris_msmon_read() adds to it. This results in a kernel oops with a call trace such as: Call trace: __ris_msmon_read+0x19c/0x64c (P) mpam_restore_mbwu_state+0xa0/0xe8 smp_call_on_cpu_callback+0x1c/0x38 process_one_work+0x154/0x4b4 worker_thread+0x188/0x310 kthread+0x11c/0x130 ret_from_fork+0x10/0x20 Provide a local variable for val to avoid __ris_msmon_read() dereferencing a null pointer when adding to val.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-23433 since 01/13/2026. The exploitability is told to be difficult. The attack needs to be approached locally. There are known technical details, but no exploit is available.

Upgrading to version 6.19.10 or 7.0-rc5 eliminates this vulnerability. Applying the patch ac3e12bc195786d3d44d730b5b2259fd36191848/4ad79c874e53ebb7fe3b8ae7ac6c858a2121f415 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.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 7.0-rc1
• 7.0-rc2
• 7.0-rc3
• 7.0-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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