CVE-2025-38172 (GCVE-0-2025-38172)
Vulnerability from cvelistv5
Published
2025-07-03 08:36
Modified
2026-08-05 12:00
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: erofs: avoid using multiple devices with different type For multiple devices, both primary and extra devices should be the same type. `erofs_init_device` has already guaranteed that if the primary is a file-backed device, extra devices should also be regular files. However, if the primary is a block device while the extra device is a file-backed device, `erofs_init_device` will get an ENOTBLK, which is not treated as an error in `erofs_fc_get_tree`, and that leads to an UAF: erofs_fc_get_tree get_tree_bdev_flags(erofs_fc_fill_super) erofs_read_superblock erofs_init_device // sbi->dif0 is not inited yet, // return -ENOTBLK deactivate_locked_super free(sbi) if (err is -ENOTBLK) sbi->dif0.file = filp_open() // sbi UAF So if -ENOTBLK is hitted in `erofs_init_device`, it means the primary device must be a block device, and the extra device is not a block device. The error can be converted to -EINVAL.
References
Impacted products
Vendor Product Version
Linux Linux Version: fb176750266a3d7f42ebdcf28e8ba40350b27847
Version: fb176750266a3d7f42ebdcf28e8ba40350b27847
Version: fb176750266a3d7f42ebdcf28e8ba40350b27847
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/erofs/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "65115472f741ca000d7ea4a5922214f93cd1516e",
              "status": "affected",
              "version": "fb176750266a3d7f42ebdcf28e8ba40350b27847",
              "versionType": "git"
            },
            {
              "lessThan": "cd04beb9ce2773a16057248bb4fa424068ae3807",
              "status": "affected",
              "version": "fb176750266a3d7f42ebdcf28e8ba40350b27847",
              "versionType": "git"
            },
            {
              "lessThan": "9748f2f54f66743ac77275c34886a9f890e18409",
              "status": "affected",
              "version": "fb176750266a3d7f42ebdcf28e8ba40350b27847",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/erofs/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.34",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15.3",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: avoid using multiple devices with different type\n\nFor multiple devices, both primary and extra devices should be the\nsame type. `erofs_init_device` has already guaranteed that if the\nprimary is a file-backed device, extra devices should also be\nregular files.\n\nHowever, if the primary is a block device while the extra device\nis a file-backed device, `erofs_init_device` will get an ENOTBLK,\nwhich is not treated as an error in `erofs_fc_get_tree`, and that\nleads to an UAF:\n\n  erofs_fc_get_tree\n    get_tree_bdev_flags(erofs_fc_fill_super)\n      erofs_read_superblock\n        erofs_init_device  // sbi-\u003edif0 is not inited yet,\n                           // return -ENOTBLK\n      deactivate_locked_super\n        free(sbi)\n    if (err is -ENOTBLK)\n      sbi-\u003edif0.file = filp_open()  // sbi UAF\n\nSo if -ENOTBLK is hitted in `erofs_init_device`, it means the\nprimary device must be a block device, and the extra device\nis not a block device. The error can be converted to -EINVAL."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is reached only through the local mount(2)/fsconfig(2)+fsmount(2) filesystem-mount path on an erofs image plus its `device=` parameters; there is no network-facing consumer of this code.\nAC:L - The trigger is fully deterministic \u2014 an erofs image whose on-disk device table count matches the supplied `device=` options, with one such path naming a regular file instead of a block device, reliably yields -ENOTBLK and the use-after-free write on every attempt. Heap reuse of the freed `erofs_sb_info` is attacker-assisted because the free\u2192write window spans an attacker-influenceable `filp_open()` path walk that can be stalled arbitrarily, and the spray runs from the attacker\u0027s own threads.\nPR:N - The attacker needs no account or capability on the target: they only supply the malicious erofs image and/or arrange the `device=` path (which is resolved with symlink following at fill_super time, in directories such as container blob/staging dirs) to be a non-block file, while a privileged mounter \u2014 automounter, container/composefs runtime, or mount helper handling multi-device erofs images \u2014 performs the mount. This matches the kernel CNA treatment of crafted-image mount bugs (e.g. CVE-2025-38204, CVE-2025-38230, CVE-2025-38652).\nUI:R - The flaw only fires when someone mounts the attacker-supplied erofs image with the corresponding `device=` parameters; it cannot be triggered without that mount action.\nS:U - The freed object, the corrupted slab memory, and the resulting crash or escalation are all inside the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `file_inode(sbi-\u003edif0.file)-\u003ei_mode` is read back out of the freed `erofs_sb_info`; if a sprayed object has taken the slot the kernel dereferences an attacker-groomed pointer and reads memory at an attacker-chosen location, and use-after-free of a kmalloc object is generally leverageable into kernel-memory disclosure.\nI:H - `sbi-\u003edif0.file = file` writes a valid kernel `struct file *` at a fixed offset (16) into a freed generic-kmalloc chunk, clobbering whatever live object has been reallocated there \u2014 a classic UAF write primitive that overwrites pointers/state of an unrelated kernel object and is a strong stepping stone to control-flow hijacking.\nA:H - Even without grooming, the UAF read of poisoned/reused memory and the follow-on `get_tree_nodev()` path (which calls `erofs_fc_fill_super()` with `s_fs_info == NULL`, immediately writing through a NULL `sbi`) produce a kernel oops/panic, and the path also leaks a `struct file` reference on every attempt."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:00:03.095Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/65115472f741ca000d7ea4a5922214f93cd1516e"
        },
        {
          "url": "https://git.kernel.org/stable/c/cd04beb9ce2773a16057248bb4fa424068ae3807"
        },
        {
          "url": "https://git.kernel.org/stable/c/9748f2f54f66743ac77275c34886a9f890e18409"
        }
      ],
      "title": "erofs: avoid using multiple devices with different type",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38172",
    "datePublished": "2025-07-03T08:36:10.334Z",
    "dateReserved": "2025-04-16T04:51:23.991Z",
    "dateUpdated": "2026-08-05T12:00:03.095Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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