CVE-2025-39877 (GCVE-0-2025-39877)

Vulnerability from cvelistv5 – Published: 2025-09-23 06:00 – Updated: 2026-05-11 21:38
VLAI
Title
mm/damon/sysfs: fix use-after-free in state_show()
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7034 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a61ea561c87139992fe32afdee48a6f6b85d824a , < 3858c44341ad49dc7544b19cc9f9ecffaa7cc50e (git)
Affected: a61ea561c87139992fe32afdee48a6f6b85d824a , < 60d7a3d2b985a395318faa1d88da6915fad11c19 (git)
Affected: a61ea561c87139992fe32afdee48a6f6b85d824a , < 26d29b2ac87a2989071755f9828ebf839b560d4c (git)
Affected: a61ea561c87139992fe32afdee48a6f6b85d824a , < 4e87f461d61959647464a94d11ae15c011be58ce (git)
Affected: a61ea561c87139992fe32afdee48a6f6b85d824a , < 3260a3f0828e06f5f13fac69fb1999a6d60d9cff (git)
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Linux Linux Affected: 5.18
Unaffected: 0 , < 5.18 (semver)
Unaffected: 6.1.153 , ≤ 6.1.* (semver)
Unaffected: 6.6.107 , ≤ 6.6.* (semver)
Unaffected: 6.12.48 , ≤ 6.12.* (semver)
Unaffected: 6.16.8 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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            "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."
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            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm/damon/sysfs: corregir uso despu\u00e9s de liberaci\u00f3n en state_show()\n\nstate_show() lee kdamond-\u003edamon_ctx sin mantener damon_sysfs_lock. Esto permite una condici\u00f3n de carrera de uso despu\u00e9s de liberaci\u00f3n:\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 es liberado */\nmutex_lock(\u0026ctx-\u003ekdamond_lock); /* UAF */\n\n(La condici\u00f3n de carrera tambi\u00e9n puede ocurrir con damon_sysfs_kdamonds_rm_dirs() y damon_sysfs_kdamond_release(), que liberan o reemplazan el contexto bajo damon_sysfs_lock.)\n\nSoluci\u00f3n al tomar damon_sysfs_lock antes de desreferenciar el contexto, replicando el bloqueo utilizado en pid_show().\n\nEl error ha existido desde que state_show() accedi\u00f3 por primera vez a kdamond-\u003edamon_ctx."
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      "cve": "CVE-2025-39877",
      "id": "CVE-2025-39877",
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      "product_status:known_affected": "184",
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      "source": "Red Hat CSAF VEX",
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      "title": "kernel: mm/damon/sysfs: fix use-after-free in state_show()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39877.json",
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}



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Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.