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CVE-2024-56628: LoongArch: Add architecture specific huge_pte_clear()

In the Linux kernel, the following vulnerability has been resolved: LoongArch: Add architecture specific huge_pte_clear() When executing mm selftests run_vmtests.sh, there is such an error: BUG: Bad page state in process uffd-unit-tests pfn:00000 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0 flags: 0xffff0000002000(reserved|node=0|zone=0|lastcpupid=0xffff) raw: 00ffff0000002000 ffffbf0000000008 ffffbf0000000008 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set Modules linked in: snd_seq_dummy snd_seq snd_seq_device rfkill vfat fat virtio_balloon efi_pstore virtio_net pstore net_failover failover fuse nfnetlink virtio_scsi virtio_gpu virtio_dma_buf dm_multipath efivarfs CPU: 2 UID: 0 PID: 1913 Comm: uffd-unit-tests Not tainted 6.12.0 #184 Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 2/2/2022 Stack : 900000047c8ac000 0000000000000000 9000000000223a7c 900000047c8ac000 900000047c8af690 900000047c8af698 0000000000000000 900000047c8af7d8 900000047c8af7d0 900000047c8af7d0 900000047c8af5b0 0000000000000001 0000000000000001 900000047c8af698 10b3c7d53da40d26 0000010000000000 0000000000000022 0000000fffffffff fffffffffe000000 ffff800000000000 000000000000002f 0000800000000000 000000017a6d4000 90000000028f8940 0000000000000000 0000000000000000 90000000025aa5e0 9000000002905000 0000000000000000 90000000028f8940 ffff800000000000 0000000000000000 0000000000000000 0000000000000000 9000000000223a94 000000012001839c 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d ... Call Trace: [<9000000000223a94>] show_stack+0x5c/0x180 [<9000000001c3fd64>] dump_stack_lvl+0x6c/0xa0 [<900000000056aa08>] bad_page+0x1a0/0x1f0 [<9000000000574978>] free_unref_folios+0xbf0/0xd20 [<90000000004e65cc>] folios_put_refs+0x1a4/0x2b8 [<9000000000599a0c>] free_pages_and_swap_cache+0x164/0x260 [<9000000000547698>] tlb_batch_pages_flush+0xa8/0x1c0 [<9000000000547f30>] tlb_finish_mmu+0xa8/0x218 [<9000000000543cb8>] exit_mmap+0x1a0/0x360 [<9000000000247658>] __mmput+0x78/0x200 [<900000000025583c>] do_exit+0x43c/0xde8 [<9000000000256490>] do_group_exit+0x68/0x110 [<9000000000256554>] sys_exit_group+0x1c/0x20 [<9000000001c413b4>] do_syscall+0x94/0x130 [<90000000002216d8>] handle_syscall+0xb8/0x158 Disabling lock debugging due to kernel taint BUG: non-zero pgtables_bytes on freeing mm: -16384 On LoongArch system, invalid huge pte entry should be invalid_pte_table or a single _PAGE_HUGE bit rather than a zero value. And it should be the same with invalid pmd entry, since pmd_none() is called by function free_pgd_range() and pmd_none() return 0 by huge_pte_clear(). So single _PAGE_HUGE bit is also treated as a valid pte table and free_pte_range() will be called in free_pmd_range(). free_pmd_range() pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (pmd_none_or_clear_bad(pmd)) continue; free_pte_range(tlb, pmd, addr); } while (pmd++, addr = next, addr != end); Here invalid_pte_table is used for both invalid huge pte entry and pmd entry.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux memory-management bug specific to LoongArch can mishandle huge-page table cleanup. A low-privileged local user may be able to trigger kernel memory corruption with potentially severe confidentiality, integrity, and availability impact. The supplied evidence shows test failures and a fix, but not proven real-world compromise.

Executive priority

Promptly inventory LoongArch systems and expedite patching where untrusted local users or workloads exist. Other architectures are not identified as affected by the supplied evidence. This is high priority because potential impact is severe, although active exploitation is not reported.

Technical view

LoongArch lacked an architecture-specific huge_pte_clear(). Clearing a huge-page entry incorrectly could let kernel cleanup treat it as a valid page-table reference, causing improper page freeing, bad page state, and incorrect page-table accounting. Referenced stable commits correct the invalid-entry representation.

Likely exposure

Exposure is limited to LoongArch Linux systems using affected kernels and huge-page memory-management paths. The supplied data lists versions including 5.19, 6.1.120, 6.6.66, 6.12.5, and 6.13, but does not clearly define range boundaries. Confirm distribution builds and backports with vendor guidance.

Exploitation context

CVSS 3.1 scores this 7.8: local access, low complexity, low privileges, and no user interaction. It is not remotely reachable under the stated vector. The CVE is not in KEV, and supplied sources do not report active exploitation or demonstrate a working exploit.

Researcher notes

A zeroed huge PTE is not the correct LoongArch invalid entry. During address-space teardown, cleanup can misclassify it as a PTE table and invoke free_pte_range(), producing bad-page-state and negative page-table accounting errors. Practical exploitability beyond the CVSS assumptions remains unestablished.

Mitigation direction

  • Apply a vendor-supported kernel update incorporating the referenced LoongArch huge_pte_clear() fix.
  • Reboot updated systems and confirm the corrected kernel is running.
  • Until patched, reduce low-privileged local access to affected LoongArch hosts.
  • Consult the operating-system vendor if the package's backport status is unclear.

Validation and detection

  • Confirm whether each system uses the LoongArch architecture.
  • Record the running kernel and distribution package versions.
  • Compare package changelogs or source against the referenced stable fixes.
  • After updating, verify the fixed kernel became active following reboot.
  • Review kernel logs for bad-page-state or non-zero pgtables_bytes messages.
Prepared
Confidence
medium
Sources
7

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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CVE-2024-56628 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
1ADP providers
6Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-56628Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

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

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux09cfefb7fa70c3af011b0db0a513fd80b2f18abc, 09cfefb7fa70c3af011b0db0a513fd80b2f18abc, 09cfefb7fa70c3af011b0db0a513fd80b2f18abc, 09cfefb7fa70c3af011b0db0a513fd80b2f18abcunaffected
LinuxLinux5.19, 0, 6.1.120, 6.6.66, 6.12.5, 6.13affected
Weakness

CWE details

No CWE listed

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