CVE-2025-21876

Technical Description

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

iommu/vt-d: Fix suspicious RCU usage

Commit <d74169ceb0d2> ("iommu/vt-d: Allocate DMAR fault interrupts

locally") moved the call to enable_drhd_fault_handling() to a code

path that does not hold any lock while traversing the drhd list. Fix

it by ensuring the dmar_global_lock lock is held when traversing the

drhd list.

Without this fix, the following warning is triggered:

=============================

WARNING: suspicious RCU usage

6.14.0-rc3 #55 Not tainted

-----------------------------

drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 1

2 locks held by cpuhp/1/23:

#0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0

#1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0

stack backtrace:

CPU: 1 UID: 0 PID: 23 Comm

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References