CVE-2025-39816

Full vulnerability record from the local CVENow database.
Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths Since the buffers are mapped from userspace, it is prudent to use READ_ONCE() to read the value into a local variable, and use that for any other actions taken. Having a stable read of the buffer length avoids worrying about it changing after checking, or being read multiple times. Similarly, the buffer may well change in between it being picked and being committed. Ensure the looping for incremental ring buffer commit stops if it hits a zero sized buffer, as no further progress can be made at that point.
Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-16 13:15:56.790000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
{
  "id": "CVE-2025-39816",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-09-16T13:15:56.790",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths\n\nSince the buffers are mapped from userspace, it is prudent to use\nREAD_ONCE() to read the value into a local variable, and use that for\nany other actions taken. Having a stable read of the buffer length\navoids worrying about it changing after checking, or being read multiple\ntimes.\n\nSimilarly, the buffer may well change in between it being picked and\nbeing committed. Ensure the looping for incremental ring buffer commit\nstops if it hits a zero sized buffer, as no further progress can be made\nat that point."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nio_uring/kbuf: siempre usar READ_ONCE() para leer las longitudes de búfer proporcionadas por el anillo\n\nDado que los búferes se mapean desde el espacio de usuario, es prudente usar READ_ONCE() para leer el valor en una variable local y usarla para cualquier otra acción realizada. Tener una lectura estable de la longitud del búfer evita preocuparse de que cambie después de la verificación o de que se lea varias veces.\n\nDe manera similar, el búfer bien podría cambiar entre el momento en que se selecciona y el momento en que se confirma. Asegurar que el bucle para la confirmación incremental del búfer de anillo se detenga si encuentra un búfer de tamaño cero, ya que no se puede avanzar más en ese punto."
    }
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              "versionType": "original_commit_for_fix",
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}