fkie_cve-2025-40124
Vulnerability from fkie_nvd
Published
2025-11-12 11:15
Modified
2025-11-12 16:19
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: sparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III Anthony Yznaga tracked down that a BUG_ON in ext4 code with large folios enabled resulted from copy_from_user() returning impossibly large values greater than the size to be copied. This lead to __copy_from_iter() returning impossible values instead of the actual number of bytes it was able to copy. The BUG_ON has been reported in https://lore.kernel.org/r/b14f55642207e63e907965e209f6323a0df6dcee.camel@physik.fu-berlin.de The referenced commit introduced exception handlers on user-space memory references in copy_from_user and copy_to_user. These handlers return from the respective function and calculate the remaining bytes left to copy using the current register contents. The exception handlers expect that %o2 has already been masked during the bulk copy loop, but the masking was performed after that loop. This will fix the return value of copy_from_user and copy_to_user in the faulting case. The behaviour of memcpy stays unchanged.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1198077606aeffb102587c6ea079ce99641c99d4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1857cdca12c4aff58bf26a7005a4d02850c29927
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/47b49c06eb62504075f0f2e2227aee2e2c2a58b3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5ef9c94d7110e90260c06868cf1dcf899b9f25ee
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/91eda032eb16e5d2be27c95584665bc555bb5a90
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/dc766c4830a7e1e1ee9d7f77d4ab344f2eb23c8e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e50377c6b3f278c9f3ef017ffce17f5fcc9dace4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fdd43fe6d286f27b826572457a89c926f97e2d3a
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III\n\nAnthony Yznaga tracked down that a BUG_ON in ext4 code with large folios\nenabled resulted from copy_from_user() returning impossibly large values\ngreater than the size to be copied. This lead to __copy_from_iter()\nreturning impossible values instead of the actual number of bytes it was\nable to copy.\n\nThe BUG_ON has been reported in\nhttps://lore.kernel.org/r/b14f55642207e63e907965e209f6323a0df6dcee.camel@physik.fu-berlin.de\n\nThe referenced commit introduced exception handlers on user-space memory\nreferences in copy_from_user and copy_to_user. These handlers return from\nthe respective function and calculate the remaining bytes left to copy\nusing the current register contents. The exception handlers expect that\n%o2 has already been masked during the bulk copy loop, but the masking was\nperformed after that loop. This will fix the return value of copy_from_user\nand copy_to_user in the faulting case. The behaviour of memcpy stays\nunchanged."
    }
  ],
  "id": "CVE-2025-40124",
  "lastModified": "2025-11-12T16:19:12.850",
  "metrics": {},
  "published": "2025-11-12T11:15:41.920",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1198077606aeffb102587c6ea079ce99641c99d4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1857cdca12c4aff58bf26a7005a4d02850c29927"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/47b49c06eb62504075f0f2e2227aee2e2c2a58b3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5ef9c94d7110e90260c06868cf1dcf899b9f25ee"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/91eda032eb16e5d2be27c95584665bc555bb5a90"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/dc766c4830a7e1e1ee9d7f77d4ab344f2eb23c8e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e50377c6b3f278c9f3ef017ffce17f5fcc9dace4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fdd43fe6d286f27b826572457a89c926f97e2d3a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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