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CVE Record

CVE-2022-48731: mm/kmemleak: avoid scanning potential huge holes

In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid scanning potential huge holes When using devm_request_free_mem_region() and devm_memremap_pages() to add ZONE_DEVICE memory, if requested free mem region's end pfn were huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see move_pfn_range_to_zone()). Thus it creates a huge hole between node_start_pfn() and node_end_pfn(). We found on some AMD APUs, amdkfd requested such a free mem region and created a huge hole. In such a case, following code snippet was just doing busy test_bit() looping on the huge hole. for (pfn = start_pfn; pfn < end_pfn; pfn++) { struct page *page = pfn_to_online_page(pfn); if (!page) continue; ... } So we got a soft lockup: watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221] CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1 RIP: 0010:pfn_to_online_page+0x5/0xd0 Call Trace: ? kmemleak_scan+0x16a/0x440 kmemleak_write+0x306/0x3a0 ? common_file_perm+0x72/0x170 full_proxy_write+0x5c/0x90 vfs_write+0xb9/0x260 ksys_write+0x67/0xe0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae I did some tests with the patch. (1) amdgpu module unloaded before the patch: real 0m0.976s user 0m0.000s sys 0m0.968s after the patch: real 0m0.981s user 0m0.000s sys 0m0.973s (2) amdgpu module loaded before the patch: real 0m35.365s user 0m0.000s sys 0m35.354s after the patch: real 0m1.049s user 0m0.000s sys 0m1.042s

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-48731 is a Linux kernel availability issue. Under specific memory-mapping conditions, kernel memory leak scanning can waste CPU walking a huge empty memory range, causing a soft lockup. The published evidence points to local impact and observed AMD APU graphics conditions, not remote compromise or data exposure.

Executive priority

Treat this as a targeted availability maintenance issue. It should be patched through normal kernel update channels, with higher priority for Linux fleets using affected kernels and AMD graphics stacks. It does not currently justify emergency remote-exploitation response based on the supplied evidence.

Technical view

The flaw is in Linux kernel kmemleak scanning of PFN ranges after ZONE_DEVICE memory is added through devm_request_free_mem_region() and devm_memremap_pages(). A very large end PFN can create a huge node hole, making kmemleak loop over absent pages and trigger a soft lockup. Fixes skip these holes in stable kernel commits.

Likely exposure

Exposure is most likely on affected Linux kernels where kmemleak is enabled and hardware or drivers create large ZONE_DEVICE memory holes. The source specifically cites AMD APUs with amdgpu/amdkfd involvement. Systems without kmemleak use or without the affected kernel ranges are less likely exposed.

Exploitation context

The CVSS vector is local, low-privilege, no user interaction, availability-only. The bundle does not show KEV listing or public active exploitation. Evidence supports denial-of-service risk under specific kernel memory and driver conditions, not remote code execution or privilege escalation.

Researcher notes

Focus validation on kernel versions, kmemleak configuration, ZONE_DEVICE memory users, and whether stable fixes are backported. The description includes performance before and after the patch, but does not provide a complete affected-version matrix for every distribution kernel.

Mitigation direction

  • Update to a kernel build containing the referenced stable fixes.
  • Check Linux distribution advisories for backported CVE-2022-48731 patches.
  • Prioritize systems using affected kernels with kmemleak enabled.
  • Review AMD APU or amdgpu/amdkfd hosts for higher relevance.
  • If patch status is unclear, follow vendor kernel guidance.

Validation and detection

  • Inventory Linux kernel versions across affected systems.
  • Confirm whether kmemleak support is enabled in deployed kernels.
  • Check vendor kernel changelogs for CVE-2022-48731 or the stable commits.
  • Identify systems using AMD APU graphics or amdgpu/amdkfd.
  • Monitor for kernel soft lockup messages during memory diagnostics.
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

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2022-48731 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
2ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2022-48731Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378, 4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378, 4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378, 4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378, 4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378unaffected
LinuxLinux4.14, 0, 5.4.178, 5.10.99, 5.15.22, 5.16.8, 5.17affected
Weakness

CWE details

No CWE listed

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