CVE-2025-40246 (GCVE-0-2025-40246)

Vulnerability from cvelistv5 – Published: 2025-12-04 16:08 – Updated: 2026-05-11 21:45
VLAI
Title
xfs: fix out of bounds memory read error in symlink repair
Summary
In the Linux kernel, the following vulnerability has been resolved: xfs: fix out of bounds memory read error in symlink repair xfs/286 produced this report on my test fleet: ================================================================== BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110 Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184): memcpy_orig+0x54/0x110 xrep_symlink_salvage_inline+0xb3/0xf0 [xfs] xrep_symlink_salvage+0x100/0x110 [xfs] xrep_symlink+0x2e/0x80 [xfs] xrep_attempt+0x61/0x1f0 [xfs] xfs_scrub_metadata+0x34f/0x5c0 [xfs] xfs_ioc_scrubv_metadata+0x387/0x560 [xfs] xfs_file_ioctl+0xe23/0x10e0 [xfs] __x64_sys_ioctl+0x76/0xc0 do_syscall_64+0x4e/0x1e0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128 allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago): xfs_init_local_fork+0x79/0xe0 [xfs] xfs_iformat_local+0xa4/0x170 [xfs] xfs_iformat_data_fork+0x148/0x180 [xfs] xfs_inode_from_disk+0x2cd/0x480 [xfs] xfs_iget+0x450/0xd60 [xfs] xfs_bulkstat_one_int+0x6b/0x510 [xfs] xfs_bulkstat_iwalk+0x1e/0x30 [xfs] xfs_iwalk_ag_recs+0xdf/0x150 [xfs] xfs_iwalk_run_callbacks+0xb9/0x190 [xfs] xfs_iwalk_ag+0x1dc/0x2f0 [xfs] xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs] xfs_iwalk+0xa4/0xd0 [xfs] xfs_bulkstat+0xfa/0x170 [xfs] xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs] xfs_file_ioctl+0xbf2/0x10e0 [xfs] __x64_sys_ioctl+0x76/0xc0 do_syscall_64+0x4e/0x1e0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy) 3d744dd94e92690f00a04398d2bd8631dcef1954 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014 ================================================================== On further analysis, I realized that the second parameter to min() is not correct. xfs_ifork::if_bytes is the size of the xfs_ifork::if_data buffer. if_bytes can be smaller than the data fork size because: (a) the forkoff code tries to keep the data area as large as possible (b) for symbolic links, if_bytes is the ondisk file size + 1 (c) forkoff is always a multiple of 8. Case in point: for a single-byte symlink target, forkoff will be 8 but the buffer will only be 2 bytes long. In other words, the logic here is wrong and we walk off the end of the incore buffer. Fix that.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 2651923d8d8db00a57665822f017fa7c76758044 , < 7c2d68e091584149fe89bcbaf9b99b3162d46ee7 (git)
Affected: 2651923d8d8db00a57665822f017fa7c76758044 , < 81a8685cac4bf081c93a7df591644f4f80240bb9 (git)
Affected: 2651923d8d8db00a57665822f017fa7c76758044 , < 678e1cc2f482e0985a0613ab4a5bf89c497e5acc (git)
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Linux Linux Affected: 6.10
Unaffected: 0 , < 6.10 (semver)
Unaffected: 6.12.60 , ≤ 6.12.* (semver)
Unaffected: 6.17.10 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/xfs/scrub/symlink_repair.c"
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              "versionType": "git"
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.10"
            },
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              "version": "0",
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            },
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              "versionType": "semver"
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              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
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                },
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                  "versionEndExcluding": "6.17.10",
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                },
                {
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                  "versionEndExcluding": "6.18",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix out of bounds memory read error in symlink repair\n\nxfs/286 produced this report on my test fleet:\n\n ==================================================================\n BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110\n\n Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184):\n  memcpy_orig+0x54/0x110\n  xrep_symlink_salvage_inline+0xb3/0xf0 [xfs]\n  xrep_symlink_salvage+0x100/0x110 [xfs]\n  xrep_symlink+0x2e/0x80 [xfs]\n  xrep_attempt+0x61/0x1f0 [xfs]\n  xfs_scrub_metadata+0x34f/0x5c0 [xfs]\n  xfs_ioc_scrubv_metadata+0x387/0x560 [xfs]\n  xfs_file_ioctl+0xe23/0x10e0 [xfs]\n  __x64_sys_ioctl+0x76/0xc0\n  do_syscall_64+0x4e/0x1e0\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128\n\n allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago):\n  xfs_init_local_fork+0x79/0xe0 [xfs]\n  xfs_iformat_local+0xa4/0x170 [xfs]\n  xfs_iformat_data_fork+0x148/0x180 [xfs]\n  xfs_inode_from_disk+0x2cd/0x480 [xfs]\n  xfs_iget+0x450/0xd60 [xfs]\n  xfs_bulkstat_one_int+0x6b/0x510 [xfs]\n  xfs_bulkstat_iwalk+0x1e/0x30 [xfs]\n  xfs_iwalk_ag_recs+0xdf/0x150 [xfs]\n  xfs_iwalk_run_callbacks+0xb9/0x190 [xfs]\n  xfs_iwalk_ag+0x1dc/0x2f0 [xfs]\n  xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs]\n  xfs_iwalk+0xa4/0xd0 [xfs]\n  xfs_bulkstat+0xfa/0x170 [xfs]\n  xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs]\n  xfs_file_ioctl+0xbf2/0x10e0 [xfs]\n  __x64_sys_ioctl+0x76/0xc0\n  do_syscall_64+0x4e/0x1e0\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy)  3d744dd94e92690f00a04398d2bd8631dcef1954\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014\n ==================================================================\n\nOn further analysis, I realized that the second parameter to min() is\nnot correct.  xfs_ifork::if_bytes is the size of the xfs_ifork::if_data\nbuffer.  if_bytes can be smaller than the data fork size because:\n\n(a) the forkoff code tries to keep the data area as large as possible\n(b) for symbolic links, if_bytes is the ondisk file size + 1\n(c) forkoff is always a multiple of 8.\n\nCase in point: for a single-byte symlink target, forkoff will be\n8 but the buffer will only be 2 bytes long.\n\nIn other words, the logic here is wrong and we walk off the end of the\nincore buffer.  Fix that."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:45:37.260Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7c2d68e091584149fe89bcbaf9b99b3162d46ee7"
        },
        {
          "url": "https://git.kernel.org/stable/c/81a8685cac4bf081c93a7df591644f4f80240bb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/678e1cc2f482e0985a0613ab4a5bf89c497e5acc"
        }
      ],
      "title": "xfs: fix out of bounds memory read error in symlink repair",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40246",
    "datePublished": "2025-12-04T16:08:09.751Z",
    "dateReserved": "2025-04-16T07:20:57.181Z",
    "dateUpdated": "2026-05-11T21:45:37.260Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-40246",
      "date": "2026-06-04",
      "epss": "0.00023",
      "percentile": "0.0685"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40246\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-04T16:16:17.970\",\"lastModified\":\"2025-12-04T17:15:08.283\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nxfs: fix out of bounds memory read error in symlink repair\\n\\nxfs/286 produced this report on my test fleet:\\n\\n ==================================================================\\n BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110\\n\\n Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184):\\n  memcpy_orig+0x54/0x110\\n  xrep_symlink_salvage_inline+0xb3/0xf0 [xfs]\\n  xrep_symlink_salvage+0x100/0x110 [xfs]\\n  xrep_symlink+0x2e/0x80 [xfs]\\n  xrep_attempt+0x61/0x1f0 [xfs]\\n  xfs_scrub_metadata+0x34f/0x5c0 [xfs]\\n  xfs_ioc_scrubv_metadata+0x387/0x560 [xfs]\\n  xfs_file_ioctl+0xe23/0x10e0 [xfs]\\n  __x64_sys_ioctl+0x76/0xc0\\n  do_syscall_64+0x4e/0x1e0\\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n\\n kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128\\n\\n allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago):\\n  xfs_init_local_fork+0x79/0xe0 [xfs]\\n  xfs_iformat_local+0xa4/0x170 [xfs]\\n  xfs_iformat_data_fork+0x148/0x180 [xfs]\\n  xfs_inode_from_disk+0x2cd/0x480 [xfs]\\n  xfs_iget+0x450/0xd60 [xfs]\\n  xfs_bulkstat_one_int+0x6b/0x510 [xfs]\\n  xfs_bulkstat_iwalk+0x1e/0x30 [xfs]\\n  xfs_iwalk_ag_recs+0xdf/0x150 [xfs]\\n  xfs_iwalk_run_callbacks+0xb9/0x190 [xfs]\\n  xfs_iwalk_ag+0x1dc/0x2f0 [xfs]\\n  xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs]\\n  xfs_iwalk+0xa4/0xd0 [xfs]\\n  xfs_bulkstat+0xfa/0x170 [xfs]\\n  xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs]\\n  xfs_file_ioctl+0xbf2/0x10e0 [xfs]\\n  __x64_sys_ioctl+0x76/0xc0\\n  do_syscall_64+0x4e/0x1e0\\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\\n\\n CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy)  3d744dd94e92690f00a04398d2bd8631dcef1954\\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014\\n ==================================================================\\n\\nOn further analysis, I realized that the second parameter to min() is\\nnot correct.  xfs_ifork::if_bytes is the size of the xfs_ifork::if_data\\nbuffer.  if_bytes can be smaller than the data fork size because:\\n\\n(a) the forkoff code tries to keep the data area as large as possible\\n(b) for symbolic links, if_bytes is the ondisk file size + 1\\n(c) forkoff is always a multiple of 8.\\n\\nCase in point: for a single-byte symlink target, forkoff will be\\n8 but the buffer will only be 2 bytes long.\\n\\nIn other words, the logic here is wrong and we walk off the end of the\\nincore buffer.  Fix that.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/678e1cc2f482e0985a0613ab4a5bf89c497e5acc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7c2d68e091584149fe89bcbaf9b99b3162d46ee7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/81a8685cac4bf081c93a7df591644f4f80240bb9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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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.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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