CVE-2025-21876 Affecting reiserfs-kmp-default package, versions <6.4.0-150600.23.47.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES156-REISERFSKMPDEFAULT-9684036
- published10 Apr 2025
- disclosed9 Apr 2025
Introduced: 9 Apr 2025
NewCVE-2025-21876 (opens in a new tab)How to fix?
Upgrade SLES:15.6 reiserfs-kmp-default to version 6.4.0-150600.23.47.2 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream reiserfs-kmp-default package and not the reiserfs-kmp-default package as distributed by SLES.
See How to fix? for SLES:15.6 relevant fixed versions and status.
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: cpuhp/1 Not tainted 6.14.0-rc3 #55 Call Trace: <TASK> dump_stack_lvl+0xb7/0xd0 lockdep_rcu_suspicious+0x159/0x1f0 ? __pfx_enable_drhd_fault_handling+0x10/0x10 enable_drhd_fault_handling+0x151/0x180 cpuhp_invoke_callback+0x1df/0x990 cpuhp_thread_fun+0x1ea/0x2c0 smpboot_thread_fn+0x1f5/0x2e0 ? __pfx_smpboot_thread_fn+0x10/0x10 kthread+0x12a/0x2d0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x4a/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK>
Holding the lock in enable_drhd_fault_handling() triggers a lockdep splat about a possible deadlock between dmar_global_lock and cpu_hotplug_lock. This is avoided by not holding dmar_global_lock when calling iommu_device_register(), which initiates the device probe process.
References
- https://www.suse.com/security/cve/CVE-2025-21876.html
- https://bugzilla.suse.com/1240179
- https://git.kernel.org/stable/c/4117c72938493a77ab53cc4b8284be8fb6ec8065
- https://git.kernel.org/stable/c/b150654f74bf0df8e6a7936d5ec51400d9ec06d8
- https://git.kernel.org/stable/c/c603ccbe91d189849e1439134598ec567088dcec