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CVE-2026-23025: mm/page_alloc: prevent pcp corruption with SMP=n

In the Linux kernel, the following vulnerability has been resolved: mm/page_alloc: prevent pcp corruption with SMP=n The kernel test robot has reported: BUG: spinlock trylock failure on UP on CPU#0, kcompactd0/28 lock: 0xffff888807e35ef0, .magic: dead4ead, .owner: kcompactd0/28, .owner_cpu: 0 CPU: 0 UID: 0 PID: 28 Comm: kcompactd0 Not tainted 6.18.0-rc5-00127-ga06157804399 #1 PREEMPT 8cc09ef94dcec767faa911515ce9e609c45db470 Call Trace: <IRQ> __dump_stack (lib/dump_stack.c:95) dump_stack_lvl (lib/dump_stack.c:123) dump_stack (lib/dump_stack.c:130) spin_dump (kernel/locking/spinlock_debug.c:71) do_raw_spin_trylock (kernel/locking/spinlock_debug.c:?) _raw_spin_trylock (include/linux/spinlock_api_smp.h:89 kernel/locking/spinlock.c:138) __free_frozen_pages (mm/page_alloc.c:2973) ___free_pages (mm/page_alloc.c:5295) __free_pages (mm/page_alloc.c:5334) tlb_remove_table_rcu (include/linux/mm.h:? include/linux/mm.h:3122 include/asm-generic/tlb.h:220 mm/mmu_gather.c:227 mm/mmu_gather.c:290) ? __cfi_tlb_remove_table_rcu (mm/mmu_gather.c:289) ? rcu_core (kernel/rcu/tree.c:?) rcu_core (include/linux/rcupdate.h:341 kernel/rcu/tree.c:2607 kernel/rcu/tree.c:2861) rcu_core_si (kernel/rcu/tree.c:2879) handle_softirqs (arch/x86/include/asm/jump_label.h:36 include/trace/events/irq.h:142 kernel/softirq.c:623) __irq_exit_rcu (arch/x86/include/asm/jump_label.h:36 kernel/softirq.c:725) irq_exit_rcu (kernel/softirq.c:741) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1052) </IRQ> <TASK> RIP: 0010:_raw_spin_unlock_irqrestore (arch/x86/include/asm/preempt.h:95 include/linux/spinlock_api_smp.h:152 kernel/locking/spinlock.c:194) free_pcppages_bulk (mm/page_alloc.c:1494) drain_pages_zone (include/linux/spinlock.h:391 mm/page_alloc.c:2632) __drain_all_pages (mm/page_alloc.c:2731) drain_all_pages (mm/page_alloc.c:2747) kcompactd (mm/compaction.c:3115) kthread (kernel/kthread.c:465) ? __cfi_kcompactd (mm/compaction.c:3166) ? __cfi_kthread (kernel/kthread.c:412) ret_from_fork (arch/x86/kernel/process.c:164) ? __cfi_kthread (kernel/kthread.c:412) ret_from_fork_asm (arch/x86/entry/entry_64.S:255) </TASK> Matthew has analyzed the report and identified that in drain_page_zone() we are in a section protected by spin_lock(&pcp->lock) and then get an interrupt that attempts spin_trylock() on the same lock. The code is designed to work this way without disabling IRQs and occasionally fail the trylock with a fallback. However, the SMP=n spinlock implementation assumes spin_trylock() will always succeed, and thus it's normally a no-op. Here the enabled lock debugging catches the problem, but otherwise it could cause a corruption of the pcp structure. The problem has been introduced by commit 574907741599 ("mm/page_alloc: leave IRQs enabled for per-cpu page allocations"). The pcp locking scheme recognizes the need for disabling IRQs to prevent nesting spin_trylock() sections on SMP=n, but the need to prevent the nesting in spin_lock() has not been recognized. Fix it by introducing local wrappers that change the spin_lock() to spin_lock_iqsave() with SMP=n and use them in all places that do spin_lock(&pcp->lock). [vbabka@suse.cz: add pcp_ prefix to the spin_lock_irqsave wrappers, per Steven]

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can corrupt per-CPU page allocator state on kernels built without SMP support. It was found by automated kernel testing, not reported as active exploitation. Business impact depends on whether affected Linux kernels or embedded products use non-SMP builds.

Executive priority

Treat as a targeted kernel maintenance issue, not a broad emergency. Prioritize systems using custom, embedded, or vendor Linux builds where SMP may be disabled, and track supplier fixes.

Technical view

A locking mismatch in mm/page_alloc can allow nested access to pcp->lock when SMP=n and interrupts remain enabled. UP spin_trylock behavior can mask failure, with debug catching a spinlock trylock failure and non-debug builds risking pcp structure corruption.

Likely exposure

Exposure appears limited to Linux kernel builds using SMP=n, especially versions containing commit 574907741599 before stable fixes. The bundle lists affected Linux version markers including 6.2, 6.1.162, 6.6.122, 6.12.67, 6.18.7, and 6.19, but product impact needs vendor verification.

Exploitation context

No source in the bundle claims active exploitation, and KEV is false. Evidence is a kernel test robot report and upstream stable fixes. The practical attackability is not established in the provided sources.

Researcher notes

The issue was introduced by commit 574907741599. The fix changes pcp spin_lock use to irqsave wrappers on SMP=n, preventing interrupt nesting around per-cpu page allocator locks.

Mitigation direction

  • Update affected Linux kernels to vendor packages containing the listed stable fixes.
  • Check distribution or device vendor advisories before relying on version strings alone.
  • For Siemens environments, review SSA-253495 for product-specific guidance.
  • If no fixed package exists, follow vendor mitigation guidance rather than improvising kernel changes.

Validation and detection

  • Inventory Linux kernel versions and confirm whether CONFIG_SMP is disabled.
  • Compare deployed kernels against the listed stable fix commits and vendor advisories.
  • Review kernel logs for related spinlock debug or page allocator corruption indicators.
  • Map embedded or appliance Linux use through supplier SBOMs or firmware notices.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
7Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

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  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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ADP provider summaries

siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxd1da921452b3ee7e07383c12955ab1c6f3b08752, 5749077415994eb02d660b2559b9d8278521e73d, 5749077415994eb02d660b2559b9d8278521e73d, 5749077415994eb02d660b2559b9d8278521e73d, 5749077415994eb02d660b2559b9d8278521e73d, 6.1.57unaffected
LinuxLinux6.2, 0, 6.1.162, 6.6.122, 6.12.67, 6.18.7, 6.19affected
Weakness

CWE details

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