CVE-2025-39877 (GCVE-0-2025-39877)
Vulnerability from cvelistv5
Published
2025-09-23 06:00
Modified
2025-09-29 06:01
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: fix use-after-free in state_show() state_show() reads kdamond->damon_ctx without holding damon_sysfs_lock. This allows a use-after-free race: CPU 0 CPU 1 ----- ----- state_show() damon_sysfs_turn_damon_on() ctx = kdamond->damon_ctx; mutex_lock(&damon_sysfs_lock); damon_destroy_ctx(kdamond->damon_ctx); kdamond->damon_ctx = NULL; mutex_unlock(&damon_sysfs_lock); damon_is_running(ctx); /* ctx is freed */ mutex_lock(&ctx->kdamond_lock); /* UAF */ (The race can also occur with damon_sysfs_kdamonds_rm_dirs() and damon_sysfs_kdamond_release(), which free or replace the context under damon_sysfs_lock.) Fix by taking damon_sysfs_lock before dereferencing the context, mirroring the locking used in pid_show(). The bug has existed since state_show() first accessed kdamond->damon_ctx.
References
Impacted products
Vendor Product Version
Linux Linux Version: a61ea561c87139992fe32afdee48a6f6b85d824a
Version: a61ea561c87139992fe32afdee48a6f6b85d824a
Version: a61ea561c87139992fe32afdee48a6f6b85d824a
Version: a61ea561c87139992fe32afdee48a6f6b85d824a
Version: a61ea561c87139992fe32afdee48a6f6b85d824a
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/damon/sysfs.c"
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          "vendor": "Linux",
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              "version": "6.16.8",
              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs: fix use-after-free in state_show()\n\nstate_show() reads kdamond-\u003edamon_ctx without holding damon_sysfs_lock. \nThis allows a use-after-free race:\n\nCPU 0                         CPU 1\n-----                         -----\nstate_show()                  damon_sysfs_turn_damon_on()\nctx = kdamond-\u003edamon_ctx;     mutex_lock(\u0026damon_sysfs_lock);\n                              damon_destroy_ctx(kdamond-\u003edamon_ctx);\n                              kdamond-\u003edamon_ctx = NULL;\n                              mutex_unlock(\u0026damon_sysfs_lock);\ndamon_is_running(ctx);        /* ctx is freed */\nmutex_lock(\u0026ctx-\u003ekdamond_lock); /* UAF */\n\n(The race can also occur with damon_sysfs_kdamonds_rm_dirs() and\ndamon_sysfs_kdamond_release(), which free or replace the context under\ndamon_sysfs_lock.)\n\nFix by taking damon_sysfs_lock before dereferencing the context, mirroring\nthe locking used in pid_show().\n\nThe bug has existed since state_show() first accessed kdamond-\u003edamon_ctx."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-09-29T06:01:35.845Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/3858c44341ad49dc7544b19cc9f9ecffaa7cc50e"
        },
        {
          "url": "https://git.kernel.org/stable/c/60d7a3d2b985a395318faa1d88da6915fad11c19"
        },
        {
          "url": "https://git.kernel.org/stable/c/26d29b2ac87a2989071755f9828ebf839b560d4c"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e87f461d61959647464a94d11ae15c011be58ce"
        },
        {
          "url": "https://git.kernel.org/stable/c/3260a3f0828e06f5f13fac69fb1999a6d60d9cff"
        }
      ],
      "title": "mm/damon/sysfs: fix use-after-free in state_show()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39877",
    "datePublished": "2025-09-23T06:00:48.317Z",
    "dateReserved": "2025-04-16T07:20:57.144Z",
    "dateUpdated": "2025-09-29T06:01:35.845Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39877\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-09-23T06:15:47.230\",\"lastModified\":\"2025-09-24T18:11:24.520\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/damon/sysfs: fix use-after-free in state_show()\\n\\nstate_show() reads kdamond-\u003edamon_ctx without holding damon_sysfs_lock. \\nThis allows a use-after-free race:\\n\\nCPU 0                         CPU 1\\n-----                         -----\\nstate_show()                  damon_sysfs_turn_damon_on()\\nctx = kdamond-\u003edamon_ctx;     mutex_lock(\u0026damon_sysfs_lock);\\n                              damon_destroy_ctx(kdamond-\u003edamon_ctx);\\n                              kdamond-\u003edamon_ctx = NULL;\\n                              mutex_unlock(\u0026damon_sysfs_lock);\\ndamon_is_running(ctx);        /* ctx is freed */\\nmutex_lock(\u0026ctx-\u003ekdamond_lock); /* UAF */\\n\\n(The race can also occur with damon_sysfs_kdamonds_rm_dirs() and\\ndamon_sysfs_kdamond_release(), which free or replace the context under\\ndamon_sysfs_lock.)\\n\\nFix by taking damon_sysfs_lock before dereferencing the context, mirroring\\nthe locking used in pid_show().\\n\\nThe bug has existed since state_show() first accessed kdamond-\u003edamon_ctx.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/26d29b2ac87a2989071755f9828ebf839b560d4c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3260a3f0828e06f5f13fac69fb1999a6d60d9cff\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3858c44341ad49dc7544b19cc9f9ecffaa7cc50e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4e87f461d61959647464a94d11ae15c011be58ce\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/60d7a3d2b985a395318faa1d88da6915fad11c19\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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