GHSA-RJ94-R4GM-MQJ5
Vulnerability from github – Published: 2026-08-28 09:31 – Updated: 2026-08-29 09:30In the Linux kernel, the following vulnerability has been resolved:
cxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size
The CXL r4.0 8.2.4.17.7 RAS Capability Structure has total length 0x58 bytes (CXL_RAS_CAPABILITY_LENGTH); the Header Log occupies the trailing 64 bytes at offset 0x18. CXL_HEADERLOG_SIZE was defined as SZ_512, eight times the actual on-device size.
header_log_copy() reads CXL_HEADERLOG_SIZE_U32 (128) dwords from the RAS capability iomap, overrunning the 88-byte mapping by 448 bytes. The cxl_aer_uncorrectable_error trace event memcpy()s CXL_HEADERLOG_SIZE (512) bytes from its source. For the CPER caller the source is struct cxl_ras_capability_regs::header_log[16] (64 bytes) embedded in a stack-local cxl_cper_prot_err_work_data, so the memcpy reads 448 bytes of kernel stack into the trace event ring buffer where userspace can read it via tracefs.
Set CXL_HEADERLOG_SIZE to 64 and derive CXL_HEADERLOG_SIZE_U32 from it, bringing all iomap readers into agreement on 16 dwords. Userspace tools such as rasdaemon have grown a dependency on the buggy 512-byte (128 u32) header_log layout in the cxl_aer_uncorrectable_error trace event. Add CXL_HEADERLOG_TRACE_SIZE_U32 = 128 and use it for the trace event __array and its memcpy to preserve that ABI. Both callers now pass a zero-filled u32[CXL_HEADERLOG_TRACE_SIZE_U32] staging buffer with only the first CXL_HEADERLOG_SIZE_U32 (16) entries populated from hardware; the remaining 112 u32s are zero-padded, keeping the 512-byte trace ring buffer layout intact.
[ dj: Replaced 64 with SZ_64 per RichardC ]
{
"affected": [],
"aliases": [
"CVE-2026-80662"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-28T08:16:51Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncxl: Fix CXL_HEADERLOG_SIZE to match RAS Capability size\n\nThe CXL r4.0 8.2.4.17.7 RAS Capability Structure has total length 0x58\nbytes (CXL_RAS_CAPABILITY_LENGTH); the Header Log occupies the trailing\n64 bytes at offset 0x18. CXL_HEADERLOG_SIZE was defined as SZ_512,\neight times the actual on-device size.\n\nheader_log_copy() reads CXL_HEADERLOG_SIZE_U32 (128) dwords from the\nRAS capability iomap, overrunning the 88-byte mapping by 448 bytes.\nThe cxl_aer_uncorrectable_error trace event memcpy()s CXL_HEADERLOG_SIZE\n(512) bytes from its source. For the CPER caller the source is\nstruct cxl_ras_capability_regs::header_log[16] (64 bytes) embedded in a\nstack-local cxl_cper_prot_err_work_data, so the memcpy reads 448 bytes\nof kernel stack into the trace event ring buffer where userspace can\nread it via tracefs.\n\nSet CXL_HEADERLOG_SIZE to 64 and derive CXL_HEADERLOG_SIZE_U32 from it,\nbringing all iomap readers into agreement on 16 dwords. Userspace tools\nsuch as rasdaemon have grown a dependency on the buggy 512-byte (128 u32)\nheader_log layout in the cxl_aer_uncorrectable_error trace event. Add\nCXL_HEADERLOG_TRACE_SIZE_U32 = 128 and use it for the trace event\n__array and its memcpy to preserve that ABI. Both callers now pass a\nzero-filled u32[CXL_HEADERLOG_TRACE_SIZE_U32] staging buffer with only\nthe first CXL_HEADERLOG_SIZE_U32 (16) entries populated from hardware;\nthe remaining 112 u32s are zero-padded, keeping the 512-byte trace ring\nbuffer layout intact.\n\n[ dj: Replaced 64 with SZ_64 per RichardC ]",
"id": "GHSA-rj94-r4gm-mqj5",
"modified": "2026-08-29T09:30:27Z",
"published": "2026-08-28T09:31:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80662"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6fc1919a6f2ed541484dd1f6cd93374044f8fd3d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c268f949e219f9e179558e836f457f6c5fbec416"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fc5eb0962a5e50d64e711817cc24d67df2d90528"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.