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CVE-2022-49424: iommu/mediatek: Fix NULL pointer dereference when printing dev_name

In the Linux kernel, the following vulnerability has been resolved: iommu/mediatek: Fix NULL pointer dereference when printing dev_name When larbdev is NULL (in the case I hit, the node is incorrectly set iommus = <&iommu NUM>), it will cause device_link_add() fail and kernel crashes when we try to print dev_name(larbdev). Let's fail the probe if a larbdev is NULL to avoid invalid inputs from dts. It should work for normal correct setting and avoid the crash caused by my incorrect setting. Error log: [ 18.189042][ T301] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050 ... [ 18.344519][ T301] pstate: a0400005 (NzCv daif +PAN -UAO) [ 18.345213][ T301] pc : mtk_iommu_probe_device+0xf8/0x118 [mtk_iommu] [ 18.346050][ T301] lr : mtk_iommu_probe_device+0xd0/0x118 [mtk_iommu] [ 18.346884][ T301] sp : ffffffc00a5635e0 [ 18.347392][ T301] x29: ffffffc00a5635e0 x28: ffffffd44a46c1d8 [ 18.348156][ T301] x27: ffffff80c39a8000 x26: ffffffd44a80cc38 [ 18.348917][ T301] x25: 0000000000000000 x24: ffffffd44a80cc38 [ 18.349677][ T301] x23: ffffffd44e4da4c6 x22: ffffffd44a80cc38 [ 18.350438][ T301] x21: ffffff80cecd1880 x20: 0000000000000000 [ 18.351198][ T301] x19: ffffff80c439f010 x18: ffffffc00a50d0c0 [ 18.351959][ T301] x17: ffffffffffffffff x16: 0000000000000004 [ 18.352719][ T301] x15: 0000000000000004 x14: ffffffd44eb5d420 [ 18.353480][ T301] x13: 0000000000000ad2 x12: 0000000000000003 [ 18.354241][ T301] x11: 00000000fffffad2 x10: c0000000fffffad2 [ 18.355003][ T301] x9 : a0d288d8d7142d00 x8 : a0d288d8d7142d00 [ 18.355763][ T301] x7 : ffffffd44c2bc640 x6 : 0000000000000000 [ 18.356524][ T301] x5 : 0000000000000080 x4 : 0000000000000001 [ 18.357284][ T301] x3 : 0000000000000000 x2 : 0000000000000005 [ 18.358045][ T301] x1 : 0000000000000000 x0 : 0000000000000000 [ 18.360208][ T301] Hardware name: MT6873 (DT) [ 18.360771][ T301] Call trace: [ 18.361168][ T301] dump_backtrace+0xf8/0x1f0 [ 18.361737][ T301] dump_stack_lvl+0xa8/0x11c [ 18.362305][ T301] dump_stack+0x1c/0x2c [ 18.362816][ T301] mrdump_common_die+0x184/0x40c [mrdump] [ 18.363575][ T301] ipanic_die+0x24/0x38 [mrdump] [ 18.364230][ T301] atomic_notifier_call_chain+0x128/0x2b8 [ 18.364937][ T301] die+0x16c/0x568 [ 18.365394][ T301] __do_kernel_fault+0x1e8/0x214 [ 18.365402][ T301] do_page_fault+0xb8/0x678 [ 18.366934][ T301] do_translation_fault+0x48/0x64 [ 18.368645][ T301] do_mem_abort+0x68/0x148 [ 18.368652][ T301] el1_abort+0x40/0x64 [ 18.368660][ T301] el1h_64_sync_handler+0x54/0x88 [ 18.368668][ T301] el1h_64_sync+0x68/0x6c [ 18.368673][ T301] mtk_iommu_probe_device+0xf8/0x118 [mtk_iommu] ...

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-49424 is a Linux kernel crash bug in the MediaTek IOMMU driver. If a device tree contains an invalid IOMMU reference, the driver can dereference NULL while printing a device name, causing a kernel crash. This mainly matters for MediaTek-based systems with custom or incorrect device-tree configuration.

Executive priority

Prioritize for embedded, Android, appliance, or IoT products built on MediaTek platforms. For other Linux fleets, treat as low urgency unless MediaTek hardware is present. Business impact is primarily device crash or failed boot from invalid platform configuration.

Technical view

The issue is in mtk_iommu_probe_device. When larbdev is NULL, device_link_add fails and later dev_name(larbdev) triggers a NULL pointer dereference. The upstream resolution changes probing behavior to fail when larbdev is NULL, avoiding the crash from invalid DTS input. Affected versions listed include Linux 5.15.46, 5.17.14, 5.18, 5.18.3, and 5.19.

Likely exposure

Exposure appears limited to Linux systems using the MediaTek IOMMU driver, especially embedded or mobile platforms with MediaTek SoCs and custom device trees. General-purpose Linux servers without this hardware path are unlikely to be affected.

Exploitation context

No active exploitation is indicated in the provided sources, and the CVE is not listed as KEV. The described trigger is an incorrectly configured device tree, suggesting configuration or image-build exposure rather than a typical remote attack path.

Researcher notes

The public record provides a kernel commit-level fix and crash trace, but no CVSS, CWE, exploitability analysis, or product advisories. Avoid assuming remote exploitability. Focus analysis on DTS validation, MediaTek IOMMU probe behavior, and whether downstream vendor kernels contain the upstream fix.

Mitigation direction

  • Apply a vendor kernel update that includes the referenced stable MediaTek IOMMU fix.
  • For custom kernels, verify the relevant stable commit is backported.
  • Review MediaTek device-tree IOMMU entries for invalid larb references.
  • Check platform vendor advisories for product-specific fixed kernel builds.

Validation and detection

  • Inventory Linux devices using MediaTek SoCs and the mtk_iommu driver.
  • Compare running kernel versions against vendor-fixed releases or referenced stable commits.
  • Review boot logs for MediaTek IOMMU probe crashes or NULL dereference traces.
  • Validate custom device trees against vendor hardware documentation.
Prepared
Confidence
medium
Sources
6

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

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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
0ADP providers
5Source links

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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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux77fbe028d5a3f7fc6060c4454ead9510533acd1e, 18ea450ed1b60c1bb336f5efe874f61909ce7bec, 635319a4a7444ca97124d781cd96deb277ff4d40, 635319a4a7444ca97124d781cd96deb277ff4d40, b7bf68272b6ae7c469854e2e054db1db1d158999unaffected
LinuxLinux5.18, 0, 5.15.46, 5.17.14, 5.18.3, 5.19affected
Weakness

CWE details

No CWE listed

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