tracing: Fix retry exhaustion in simple ring buffer reader swap

{
  "id": "025cf733c101c1936552371d0d3c064145d09f41003d4bf4b99fa5f54d06ea95",
  "url": "https://osv.dev/vulnerability/CVE-2026-89748",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tracing: Fix retry exhaustion in simple ring buffer reader swap",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tracing: Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. The current !retry test reverses both outcomes. It returns an error after a successful final replacement, leaving the link update complete but the reader bookkeeping unfinished. After a failed final replacement, it falls through and updates the head and reader pointers as though the replacement succeeded, which can corrupt the ring. Treat only a negative counter as exhaustion and return the documented -EBUSY error.",
    "evidence": "osv:CVE-2026-89748",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-89748",
      "aliases": [
        "CVE-2026-89748"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                {
                  "fixed": "df02489aa3aa1834659f0d20c89f7d212047d268"
                },
                {
                  "fixed": "e0d3aed7b12cf37b74c7cc5265073d0263b49cde"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89748.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "7.1.0"
                },
                {
                  "fixed": "7.2.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89748.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:52.434399624Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/df02489aa3aa1834659f0d20c89f7d212047d268",
        "https://git.kernel.org/stable/c/e0d3aed7b12cf37b74c7cc5265073d0263b49cde",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89748.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89748",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89748.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-89748",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 521377,
  "published_at": "2026-09-11T19:46:53.07+00:00"
}