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CVE Record

CVE-2022-50569: xfrm: Update ipcomp_scratches with NULL when freed

In the Linux kernel, the following vulnerability has been resolved: xfrm: Update ipcomp_scratches with NULL when freed Currently if ipcomp_alloc_scratches() fails to allocate memory ipcomp_scratches holds obsolete address. So when we try to free the percpu scratches using ipcomp_free_scratches() it tries to vfree non existent vm area. Described below: static void * __percpu *ipcomp_alloc_scratches(void) { ... scratches = alloc_percpu(void *); if (!scratches) return NULL; ipcomp_scratches does not know about this allocation failure. Therefore holding the old obsolete address. ... } So when we free, static void ipcomp_free_scratches(void) { ... scratches = ipcomp_scratches; Assigning obsolete address from ipcomp_scratches if (!scratches) return; for_each_possible_cpu(i) vfree(*per_cpu_ptr(scratches, i)); Trying to free non existent page, causing warning: trying to vfree existent vm area. ... } Fix this breakage by updating ipcomp_scrtches with NULL when scratches is freed

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

A flaw in the Linux kernel's IPsec compression code could leave a stale memory pointer behind when an internal allocation fails. If the system later tries to clean up, it could trigger a kernel warning. There is no sign this is being exploited, and no remote attack path is described. Treat as a routine kernel hygiene update.

Executive priority

Low priority. Apply through routine kernel patching cycles; no evidence of active exploitation or remote risk.

Technical view

In the Linux kernel xfrm IPComp path, ipcomp_alloc_scratches() can fail to allocate the percpu scratch pointer while the global ipcomp_scratches retains a stale prior address. A subsequent ipcomp_free_scratches() then dereferences and vfree()s an obsolete vm area, generating a "trying to vfree existent vm area" warning. The patch sets ipcomp_scratches to NULL when freed, eliminating the dangling reference.

Likely exposure

Linux systems running affected stable kernels prior to the listed fix points (4.9.331, 4.14.296, 4.19.262, 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3) that use IPsec with the IP Compression (IPComp) transform. Distribution-packaged kernels inherit the fix once rebased.

Exploitation context

No active exploitation referenced. Not listed in CISA KEV. Triggering the bug requires the rare path where IPComp percpu scratch allocation fails, then is freed, which is typically only reachable on the local kernel under memory pressure with IPsec/IPComp in use.

Researcher notes

The bug is in net/xfrm IPComp: ipcomp_alloc_scratches() can return NULL on allocation failure while the global ipcomp_scratches still holds the prior obsolete address, so ipcomp_free_scratches() later vfree()s a non-existent vm area and emits a "trying to vfree existent vm area" warning. Fix sets ipcomp_scratches = NULL on free. CVSS not provided in the bundle; CWE not assigned. Affected versions span 2.6.12 through pre-fix points listed; check stable trees for backports referenced in the kernel.org commit URLs.

Mitigation direction

  • Update to a Linux stable kernel that includes the xfrm IPComp scratches fix from your distribution.
  • Track distribution security advisories (RHEL, Ubuntu, SUSE, Debian) for backported builds.
  • Where patching is delayed, avoid configurations that rely on IPComp transforms in IPsec.
  • Reboot after kernel update to load the patched image.
  • Confirm configuration management baselines target the fixed kernel revisions.

Validation and detection

  • Inventory running kernel versions with `uname -r` against the listed fix versions per stable branch.
  • Confirm distribution package versions include the backported xfrm IPComp scratches fix.
  • Identify hosts using IPsec with IPComp via `ip xfrm state` and configuration review.
  • Check kernel logs for prior `trying to vfree existent vm area` warnings linked to ipcomp.
  • Verify post-update kernel build hash matches the patched stable release.
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

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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, 4.9.331, 4.14.296, 4.19.262, 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3, 6.1affected
Weakness

CWE details

No CWE listed

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