FKIE_CVE-2026-31652

Vulnerability from fkie_nvd - Published: 2026-04-24 15:16 - Updated: 2026-04-24 17:51
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/damon/stat: deallocate damon_call() failure leaking damon_ctx damon_stat_start() always allocates the module's damon_ctx object (damon_stat_context). Meanwhile, if damon_call() in the function fails, the damon_ctx object is not deallocated. Hence, if the damon_call() is failed, and the user writes Y to “enabled” again, the previously allocated damon_ctx object is leaked. This cannot simply be fixed by deallocating the damon_ctx object when damon_call() fails. That's because damon_call() failure doesn't guarantee the kdamond main function, which accesses the damon_ctx object, is completely finished. In other words, if damon_stat_start() deallocates the damon_ctx object after damon_call() failure, the not-yet-terminated kdamond could access the freed memory (use-after-free). Fix the leak while avoiding the use-after-free by keeping returning damon_stat_start() without deallocating the damon_ctx object after damon_call() failure, but deallocating it when the function is invoked again and the kdamond is completely terminated. If the kdamond is not yet terminated, simply return -EAGAIN, as the kdamond will soon be terminated. The issue was discovered [1] by sashiko.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/16c92e9bf55fa049ddb5e894dc0623dacd46a620
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/447f8870b484f6596d7a7130e72bd0a3f1e037bb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4c04c6b47c361612b1d70cec8f7a60b1482d1400
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/stat: deallocate damon_call() failure leaking damon_ctx\n\ndamon_stat_start() always allocates the module\u0027s damon_ctx object\n(damon_stat_context).  Meanwhile, if damon_call() in the function fails,\nthe damon_ctx object is not deallocated.  Hence, if the damon_call() is\nfailed, and the user writes Y to \u201cenabled\u201d again, the previously\nallocated damon_ctx object is leaked.\n\nThis cannot simply be fixed by deallocating the damon_ctx object when\ndamon_call() fails.  That\u0027s because damon_call() failure doesn\u0027t guarantee\nthe kdamond main function, which accesses the damon_ctx object, is\ncompletely finished.  In other words, if damon_stat_start() deallocates\nthe damon_ctx object after damon_call() failure, the not-yet-terminated\nkdamond could access the freed memory (use-after-free).\n\nFix the leak while avoiding the use-after-free by keeping returning\ndamon_stat_start() without deallocating the damon_ctx object after\ndamon_call() failure, but deallocating it when the function is invoked\nagain and the kdamond is completely terminated.  If the kdamond is not yet\nterminated, simply return -EAGAIN, as the kdamond will soon be terminated.\n\nThe issue was discovered [1] by sashiko."
    }
  ],
  "id": "CVE-2026-31652",
  "lastModified": "2026-04-24T17:51:40.810",
  "metrics": {},
  "published": "2026-04-24T15:16:44.697",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/16c92e9bf55fa049ddb5e894dc0623dacd46a620"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/447f8870b484f6596d7a7130e72bd0a3f1e037bb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4c04c6b47c361612b1d70cec8f7a60b1482d1400"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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