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CVE Record

CVE-2022-50567: fs: jfs: fix shift-out-of-bounds in dbAllocAG

In the Linux kernel, the following vulnerability has been resolved: fs: jfs: fix shift-out-of-bounds in dbAllocAG Syzbot found a crash : UBSAN: shift-out-of-bounds in dbAllocAG. The underlying bug is the missing check of bmp->db_agl2size. The field can be greater than 64 and trigger the shift-out-of-bounds. Fix this bug by adding a check of bmp->db_agl2size in dbMount since this field is used in many following functions. The upper bound for this field is L2MAXL2SIZE - L2MAXAG, thanks for the help of Dave Kleikamp. Note that, for maintenance, I reorganized error handling code of dbMount.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-50567 is a Linux kernel JFS filesystem bug that can trigger a kernel crash condition when JFS metadata contains an invalid size value. Business impact is most relevant for systems that mount JFS filesystems, especially removable, user-supplied, or otherwise untrusted images. Public sources do not report active exploitation or a CVSS score.

Executive priority

Treat as a routine-to-priority kernel maintenance item, higher for environments handling untrusted disk images or removable media. It does not currently warrant emergency response based on the provided sources.

Technical view

The issue is a shift-out-of-bounds in JFS dbAllocAG found by syzbot. The root cause is missing validation of bmp->db_agl2size; values greater than expected can trigger undefined behavior. The kernel fix adds validation in dbMount and reorganizes dbMount error handling. Multiple Linux stable commits are referenced as fixes.

Likely exposure

Exposure is likely limited to Linux systems with JFS support that mount JFS filesystems on kernels lacking the referenced fixes. Systems that do not use or mount JFS have lower practical exposure.

Exploitation context

The cited sources describe a syzbot-discovered crash, not a real-world attack. There is no KEV listing and no provided evidence of active exploitation. Practical abuse would likely require getting a vulnerable system to mount a crafted or corrupt JFS filesystem.

Researcher notes

The source bundle lacks CVSS, CWE, and detailed affected-version semantics. Analysis should focus on presence of the JFS code path and whether the stable fix is present or backported. Do not assume exploitability beyond the documented crash condition.

Mitigation direction

  • Update Linux kernels to vendor builds containing the referenced stable fixes.
  • Check distribution advisories for backported fixes for your exact kernel package.
  • Avoid mounting untrusted JFS filesystems until patched.
  • If JFS is unnecessary, consider disabling its use per vendor guidance.

Validation and detection

  • Inventory Linux systems and kernel versions.
  • Identify systems with JFS enabled or actively mounting JFS.
  • Confirm whether vendor kernels include the referenced dbMount validation fix.
  • Review kernel logs for JFS-related crashes or UBSAN shift-out-of-bounds messages.
Prepared
Confidence
medium
Sources
11

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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CVE-2022-50567 mapping review

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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
0Timeline events
0ADP providers
10Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2unaffected
LinuxLinux2.6.12, 0, 4.9.337, 4.14.303, 4.19.270, 5.4.229, 5.10.163, 5.15.86, 6.0.16, 6.1.2, 6.2affected
Weakness

CWE details

No CWE listed

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