CVE-2026-89503 (GCVE-0-2026-89503)
Vulnerability from cvelistv5
Published
2026-09-11 19:43
Modified
2026-10-19 08:47
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Fix subbuf resize race with ring_buffer_alloc_read_page() ring_buffer_alloc_read_page() is racy with ring_buffer_subbuf_order_set, it can allocate a reader page with an outdated order. This isn't a big issue, the user can still re-allocate a new reader page and try again. However, what is more problematic is if the value of subbuf_order changes in the middle of ring_buffer_alloc_read_page(). In that case, bpage->order might not match the actual allocated memory. Use bpage->order for the allocation to prevent this race.
References
Impacted products
Vendor Product Version
Linux Linux Version: bce761d757452ba5eb77e11fecc37a04b67494e7
Version: bce761d757452ba5eb77e11fecc37a04b67494e7
Version: bce761d757452ba5eb77e11fecc37a04b67494e7
Version: bce761d757452ba5eb77e11fecc37a04b67494e7
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/ring_buffer.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2313ff69bd237aad264a5913907f374f958335a2",
              "status": "affected",
              "version": "bce761d757452ba5eb77e11fecc37a04b67494e7",
              "versionType": "git"
            },
            {
              "lessThan": "2dc510957fe8fd098ab3c3147ebdf34d00cd2734",
              "status": "affected",
              "version": "bce761d757452ba5eb77e11fecc37a04b67494e7",
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              "status": "affected",
              "version": "bce761d757452ba5eb77e11fecc37a04b67494e7",
              "versionType": "git"
            },
            {
              "lessThan": "e743527c5bfdceda1095bc0a9e596e2aebb6a9c3",
              "status": "affected",
              "version": "bce761d757452ba5eb77e11fecc37a04b67494e7",
              "versionType": "git"
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        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/ring_buffer.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix subbuf resize race with ring_buffer_alloc_read_page()\n\nring_buffer_alloc_read_page() is racy with ring_buffer_subbuf_order_set,\nit can allocate a reader page with an outdated order. This isn\u0027t a big\nissue, the user can still re-allocate a new reader page and try again.\n\nHowever, what is more problematic is if the value of subbuf_order\nchanges in the middle of ring_buffer_alloc_read_page(). In that case,\nbpage-\u003eorder might not match the actual allocated memory.\n\nUse bpage-\u003eorder for the allocation to prevent this race."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached only via local tracefs: read() on per_cpu/*/trace_pipe_raw or snapshot_raw (tracing_buffers_read -\u003e ring_buffer_alloc_read_page) racing with write() to buffer_subbuf_size_kb. No network, adjacent-radio, or physical path reaches this code.\nAC:L - The attacker controls both sides: one thread reads trace_pipe_raw while another writes buffer_subbuf_size_kb. GFP_KERNEL in alloc_cpu_data sleeps, so subbuf_order can change between the two reads in ring_buffer_alloc_read_page(); the race is reliably retried.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC with no capable() check. trace_pipe_raw is 0440 and buffer_subbuf_size_kb is 0640, routinely delegated via gid=/mode= to tracing-group members on Android/Perfetto, ChromeOS, and developer systems.\nUI:N - Exploitation uses the attacker\u0027s own tracefs file descriptors and threads. No separate victim mount, click, or configuration action is required beyond the attacker holding tracefs access.\nS:U - Wrong-order page allocation and free corrupt the kernel buddy allocator and ring-buffer pages within the same OS security authority. This enables local privilege escalation but does not cross VM, IOMMU, or hardware trust boundaries.\nC:H - When bpage-\u003eorder does not match the alloc_pages() size, later copy_to_user of a stale page_size and ring_buffer_read_page memcpy/memset over-read adjacent kernel pages, and wrong-order free_pages() corrupts the buddy allocator, yielding arbitrary kernel reads.\nI:H - free_pages() with a larger order than allocated, or memcpy/memset into an undersized sub-buffer when reader_page-\u003eorder later matches the stale bpage-\u003eorder, corrupts adjacent pages and the buddy allocator, which is exploitable for arbitrary kernel writes.\nA:H - Wrong-order free_pages() and out-of-bounds writes on undersized compound pages crash the kernel via buddy-allocator corruption or oops in ring_buffer_read_page/free_read_page. The attacker can retrigger the race at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:47:54.761Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2313ff69bd237aad264a5913907f374f958335a2"
        },
        {
          "url": "https://git.kernel.org/stable/c/2dc510957fe8fd098ab3c3147ebdf34d00cd2734"
        },
        {
          "url": "https://git.kernel.org/stable/c/53106e9262a310ef2c9a9321168c03705940c678"
        },
        {
          "url": "https://git.kernel.org/stable/c/e743527c5bfdceda1095bc0a9e596e2aebb6a9c3"
        }
      ],
      "title": "ring-buffer: Fix subbuf resize race with ring_buffer_alloc_read_page()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89503",
    "datePublished": "2026-09-11T19:43:51.357Z",
    "dateReserved": "2026-09-11T19:38:34.715Z",
    "dateUpdated": "2026-10-19T08:47:54.761Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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