CVE-2026-64449 (GCVE-0-2026-64449)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-17 04:55
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: staging: vme_user: bound slave read/write to the kern_buf size The SLAVE-path helpers buffer_to_user() and buffer_from_user() copy 'count' bytes into/out of the fixed-size kern_buf (size_buf == PCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without bounding *ppos + count against size_buf. vme_user_write()/vme_user_read() only clamp count to the VME window size (image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the user-supplied slave.size -- validated against the VME address space (up to VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE. When the window exceeds 128 KiB, a write()/read() copies past the kern_buf allocation. Clamp count against size_buf in both helpers, with an early return when *ppos is already at/after the buffer end. *ppos is >= 0 here (the caller rejects negative offsets), so size_buf - *ppos cannot wrap. This mirrors the existing clamp in the MASTER-path helpers resource_to_user() / resource_from_user(), and matches the read()/write() convention of a short transfer at end-of-buffer. Found by static analysis (CodeQL taint tracking + CBMC bounded model checking) and confirmed dynamically under KASAN with the vme_fake bridge: BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80 Write of size 262144 at addr ffff888004100000 by task trigger/68 _copy_from_user+0x2d/0x80 vme_user_write+0x13e/0x240 [vme_user] vfs_write+0x1b8/0x7a0 ksys_write+0xb8/0x150
References
Impacted products
Vendor Product Version
Linux Linux Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
Version: f00a86d98a1ec3e99d352cda926fab767ba43b1f
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/staging/vme_user/vme_user.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/staging/vme_user/vme_user.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.32"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "2.6.32",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.145",
                  "versionStartIncluding": "2.6.32",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
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                  "vulnerable": true
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
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                  "versionEndExcluding": "7.2",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nstaging: vme_user: bound slave read/write to the kern_buf size\n\nThe SLAVE-path helpers buffer_to_user() and buffer_from_user() copy\n\u0027count\u0027 bytes into/out of the fixed-size kern_buf (size_buf ==\nPCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without\nbounding *ppos + count against size_buf.\n\nvme_user_write()/vme_user_read() only clamp count to the VME window size\n(image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the\nuser-supplied slave.size -- validated against the VME address space (up\nto VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE.  When the window\nexceeds 128 KiB, a write()/read() copies past the kern_buf allocation.\n\nClamp count against size_buf in both helpers, with an early return when\n*ppos is already at/after the buffer end.  *ppos is \u003e= 0 here (the caller\nrejects negative offsets), so size_buf - *ppos cannot wrap.  This mirrors\nthe existing clamp in the MASTER-path helpers resource_to_user() /\nresource_from_user(), and matches the read()/write() convention of a\nshort transfer at end-of-buffer.\n\nFound by static analysis (CodeQL taint tracking + CBMC bounded model\nchecking) and confirmed dynamically under KASAN with the vme_fake bridge:\n\n  BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80\n  Write of size 262144 at addr ffff888004100000 by task trigger/68\n    _copy_from_user+0x2d/0x80\n    vme_user_write+0x13e/0x240 [vme_user]\n    vfs_write+0x1b8/0x7a0\n    ksys_write+0xb8/0x150"
        }
      ],
      "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 vulnerable path is reached through ioctl(), lseek(), read(), and write() on a local /dev/bus/vme/s* character device. Network or physical VME-bus input is not needed.\nAC:L - The attacker can deterministically configure an aligned slave window larger than 128 KiB and select the copy offset and length; no race or external condition is required. A 256 KiB overflow was dynamically confirmed under KASAN.\nPR:L - The driver performs no capability or namespace-specific check, so an ordinary account granted access to the VME device node can configure and trigger the flaw. Although devtmpfs defaults to root-owned mode 0600, non-root access for an industrial control or service account is a reasonable deployment.\nUI:N - The attacker independently performs the configuration and malicious read or write without requiring any victim action.\nS:U - Exploitation compromises the host kernel within the same security authority. This is a standard local privilege-escalation condition, not a VM, sandbox, or IOMMU boundary escape.\nC:H - The read path copies an attacker-selected, potentially very large range of kernel memory beyond the 128 KiB allocation to userspace. This can disclose adjacent allocations, kernel pointers, credentials, and other sensitive memory.\nI:H - The write path copies attacker-controlled bytes beyond the DMA or large-kmalloc allocation, potentially across many adjacent physical pages. This provides exploitable memory corruption capable of modifying kernel objects or achieving control-flow hijacking.\nA:H - The out-of-bounds write was confirmed to trigger a KASAN kernel memory-safety failure and can corrupt or access invalid adjacent memory. A kernel oops or panic can be triggered without user interaction."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:55:52.942Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/adc8b9c30d716c362646edb45662aa1c641a154a"
        },
        {
          "url": "https://git.kernel.org/stable/c/8eff7cd4817e14dbe3b9952cce55ef52d1d38940"
        },
        {
          "url": "https://git.kernel.org/stable/c/e99f2df433c63c86c93de1e5f08f16e404388756"
        },
        {
          "url": "https://git.kernel.org/stable/c/1b495fa0d4927c88d88bf346bf311f2e26e860ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/9f32f38265014fac7f5dc9490fb01a638ce6e121"
        }
      ],
      "title": "staging: vme_user: bound slave read/write to the kern_buf size",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64449",
    "datePublished": "2026-07-25T08:51:19.537Z",
    "dateReserved": "2026-07-19T15:36:31.788Z",
    "dateUpdated": "2026-08-17T04:55:52.942Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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