CVE-2025-39877
Full vulnerability record from the local CVENow database.
Description
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
HIGH
CVSS score
7.8
(v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-23 06:15:47.230000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-09-23T06:15:47.230",
"lastModified": "2026-10-19T21:10:00.160",
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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->damon_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->damon_ctx; mutex_lock(&damon_sysfs_lock);\n damon_destroy_ctx(kdamond->damon_ctx);\n kdamond->damon_ctx = NULL;\n mutex_unlock(&damon_sysfs_lock);\ndamon_is_running(ctx); /* ctx is freed */\nmutex_lock(&ctx->kdamond_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->damon_ctx."
},
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"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm/damon/sysfs: corregir uso después de liberación en state_show()\n\nstate_show() lee kdamond->damon_ctx sin mantener damon_sysfs_lock. Esto permite una condición de carrera de uso después de liberación:\n\nCPU 0 CPU 1\n----- -----\nstate_show() damon_sysfs_turn_damon_on()\nctx = kdamond->damon_ctx; mutex_lock(&damon_sysfs_lock);\n damon_destroy_ctx(kdamond->damon_ctx);\n kdamond->damon_ctx = NULL;\n mutex_unlock(&damon_sysfs_lock);\ndamon_is_running(ctx); /* ctx es liberado */\nmutex_lock(&ctx->kdamond_lock); /* UAF */\n\n(La condición de carrera también puede ocurrir con damon_sysfs_kdamonds_rm_dirs() y damon_sysfs_kdamond_release(), que liberan o reemplazan el contexto bajo damon_sysfs_lock.)\n\nSolución 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() accedió por primera vez a kdamond->damon_ctx."
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