FKIE_CVE-2026-63815

Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - Updated: 2026-07-20 15:16
Severity
8.4 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: bound i_inline_xattr_size for non-inline-xattr inodes When the flexible_inline_xattr feature is enabled, do_read_inode() loads the on-disk i_inline_xattr_size unconditionally: if (f2fs_sb_has_flexible_inline_xattr(sbi)) fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size); but sanity_check_inode() only range-checks it when the inode also has the FI_INLINE_XATTR flag set. An inode that carries an inline dentry or inline data but not FI_INLINE_XATTR -- the normal layout for an inline directory -- therefore keeps a fully attacker-controlled i_inline_xattr_size from a crafted image. get_inline_xattr_addrs() returns that value with no flag gating, so it feeds the inode geometry: MAX_INLINE_DATA() = 4 * (CUR_ADDRS_PER_INODE - i_inline_xattr_size - 1) NR_INLINE_DENTRY() = MAX_INLINE_DATA() * BITS_PER_BYTE / (...) addrs_per_page() = CUR_ADDRS_PER_INODE - i_inline_xattr_size A large i_inline_xattr_size drives MAX_INLINE_DATA() and NR_INLINE_DENTRY() negative, so make_dentry_ptr_inline() sets d->max (int) to a negative value. The inline directory walk then compares an unsigned long bit_pos against that negative d->max, which is promoted to a huge unsigned bound, and reads far past the inline area: while (bit_pos < d->max) /* fs/f2fs/dir.c */ ... test_bit_le(bit_pos, d->bitmap) / d->dentry[bit_pos] ... Mounting a crafted image and reading such a directory triggers an out-of-bounds read in f2fs_fill_dentries(); the same underflow also corrupts ADDRS_PER_INODE for regular files. Validate i_inline_xattr_size against MAX_INLINE_XATTR_SIZE whenever the flexible_inline_xattr feature is enabled -- i.e. whenever the value is loaded from disk and consumed -- and keep the lower MIN_INLINE_XATTR_SIZE bound gated on inodes that actually carry an inline xattr, so legitimate inodes with i_inline_xattr_size == 0 are still accepted.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/16bc237ce3c483b75575abea53cfb639745311ed
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/378acf3cf19b6af6cba55e8dd1154c4e1504bae8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706",
              "status": "affected",
              "version": "6afc662e68b5f988282ff20afd58a89b1c279dca",
              "versionType": "git"
            },
            {
              "lessThan": "4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d",
              "status": "affected",
              "version": "6afc662e68b5f988282ff20afd58a89b1c279dca",
              "versionType": "git"
            },
            {
              "lessThan": "16bc237ce3c483b75575abea53cfb639745311ed",
              "status": "affected",
              "version": "6afc662e68b5f988282ff20afd58a89b1c279dca",
              "versionType": "git"
            },
            {
              "lessThan": "378acf3cf19b6af6cba55e8dd1154c4e1504bae8",
              "status": "affected",
              "version": "6afc662e68b5f988282ff20afd58a89b1c279dca",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.15"
            },
            {
              "lessThan": "4.15",
              "status": "unaffected",
              "version": "0",
              "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": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: bound i_inline_xattr_size for non-inline-xattr inodes\n\nWhen the flexible_inline_xattr feature is enabled, do_read_inode() loads\nthe on-disk i_inline_xattr_size unconditionally:\n\n\tif (f2fs_sb_has_flexible_inline_xattr(sbi))\n\t\tfi-\u003ei_inline_xattr_size = le16_to_cpu(ri-\u003ei_inline_xattr_size);\n\nbut sanity_check_inode() only range-checks it when the inode also has the\nFI_INLINE_XATTR flag set.  An inode that carries an inline dentry or inline\ndata but not FI_INLINE_XATTR -- the normal layout for an inline\ndirectory -- therefore keeps a fully attacker-controlled\ni_inline_xattr_size from a crafted image.\n\nget_inline_xattr_addrs() returns that value with no flag gating, so it\nfeeds the inode geometry:\n\n\tMAX_INLINE_DATA()  = 4 * (CUR_ADDRS_PER_INODE - i_inline_xattr_size - 1)\n\tNR_INLINE_DENTRY() = MAX_INLINE_DATA() * BITS_PER_BYTE / (...)\n\taddrs_per_page()   = CUR_ADDRS_PER_INODE - i_inline_xattr_size\n\nA large i_inline_xattr_size drives MAX_INLINE_DATA() and NR_INLINE_DENTRY()\nnegative, so make_dentry_ptr_inline() sets d-\u003emax (int) to a negative\nvalue.  The inline directory walk then compares an unsigned long bit_pos\nagainst that negative d-\u003emax, which is promoted to a huge unsigned bound,\nand reads far past the inline area:\n\n\twhile (bit_pos \u003c d-\u003emax)\t\t/* fs/f2fs/dir.c */\n\t\t... test_bit_le(bit_pos, d-\u003ebitmap) / d-\u003edentry[bit_pos] ...\n\nMounting a crafted image and reading such a directory triggers an\nout-of-bounds read in f2fs_fill_dentries(); the same underflow also\ncorrupts ADDRS_PER_INODE for regular files.\n\nValidate i_inline_xattr_size against MAX_INLINE_XATTR_SIZE whenever the\nflexible_inline_xattr feature is enabled -- i.e. whenever the value is\nloaded from disk and consumed -- and keep the lower MIN_INLINE_XATTR_SIZE\nbound gated on inodes that actually carry an inline xattr, so legitimate\ninodes with i_inline_xattr_size == 0 are still accepted."
    }
  ],
  "id": "CVE-2026-63815",
  "lastModified": "2026-07-20T15:16:48.347",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 8.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.5,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T12:16:54.527",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/16bc237ce3c483b75575abea53cfb639745311ed"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/378acf3cf19b6af6cba55e8dd1154c4e1504bae8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.