FKIE_CVE-2025-39877
Vulnerability from fkie_nvd - Published: 2025-09-23 06:15 - Updated: 2026-11-05 22:17
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_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| debian | debian_linux | 11.0 |
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},
{
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"version": "6.16.8",
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},
{
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"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
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"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."
},
{
"lang": "es",
"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."
}
],
"id": "CVE-2025-39877",
"lastModified": "2026-11-05T22:17:34.610",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"ssvcV203": [
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2025-39877",
"options": [
{
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},
{
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{
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}
],
"role": "CISA Coordinator",
"timestamp": "2026-11-05T21:12:49.483083Z",
"version": "2.0.3"
}
}
]
},
"published": "2025-09-23T06:15:47.230",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/26d29b2ac87a2989071755f9828ebf839b560d4c"
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"tags": [
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"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
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"lang": "en",
"value": "CWE-416"
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"source": "nvd@nist.gov",
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]
}
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