PT-2025-4336 · Linux+5 · Linux Kernel+5
Jann Horn
·
Published
2025-01-19
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Updated
2025-11-11
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CVE-2025-21655
CVSS v3.1
4.7
Medium
| Vector | AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H |
Name of the Vulnerable Software and Affected Versions
Linux kernel versions prior to 6.6.74
Description
The issue concerns the Linux kernel, where the function
io eventfd signal() does not properly defer another RCU period when io eventfd do signal() is invoked from an RCU callback. This leads to io eventfd free() being called directly when the reference count drops to zero, which is incorrect. The fix involves calling io eventfd put() instead of open-coding the dec-and-test and free, ensuring the freeing of io ev fd is deferred another RCU grace period.Recommendations
For Linux kernel versions prior to 6.6.74, update to version 6.6.74 or later to resolve the issue. As a temporary workaround, consider modifying the code to call
io eventfd put() instead of directly calling io eventfd free() when the reference count drops to zero, to correctly defer the freeing of io ev fd to another RCU grace period.Exploit
Fix
Use After Free
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Related Identifiers
Affected Products
Astra Linux
Linuxmint
Linux Kernel
Red Os
Suse
Ubuntu