CVE-2026-23433

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/ac3e12bc195786d3d44d730b5b2259fd36191848
• https://git.kernel.org/stable/c/4ad79c874e53ebb7fe3b8ae7ac6c858a2121f415

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