CVE-2025-21893

Summary

In the Linux kernel, the following vulnerability has been resolved:

keys: Fix UAF in key_put()

Once a key's reference count has been reduced to 0, the garbage collector thread may destroy it at any time and so key_put() is not allowed to touch the key after that point. The most key_put() is normally allowed to do is to touch key_gc_work as that's a static global variable.

However, in an effort to speed up the reclamation of quota, this is now done in key_put() once the key's usage is reduced to 0 - but now the code is looking at the key after the deadline, which is forbidden.

Fix this by using a flag to indicate that a key can be gc'd now rather than looking at the key's refcount in the garbage collector.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux9578e327b2b4935a25d49e3891b8fcca9b6c10c6 < 6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3affected
LinuxLinux9578e327b2b4935a25d49e3891b8fcca9b6c10c6 < f6a3cf833188e897c97028cd7b926e3f2cb1a8c0affected
LinuxLinux9578e327b2b4935a25d49e3891b8fcca9b6c10c6 < 75845c6c1a64483e9985302793dbf0dfa5f71e32affected
LinuxLinux6.10affected
LinuxLinux0 < 6.10unaffected
LinuxLinux6.12.21 <= 6.12.*unaffected
LinuxLinux6.13.9 <= 6.13.*unaffected
LinuxLinux6.14 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References