CVE-2021-47123: io_uring: fix ltout double free on completion race

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-15 · updated 2026-08-04
Weakness: CWE-415

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix ltout double free on completion race Always remove linked timeout on io_link_timeout_fn() from the master request link list, otherwise we may get use-after-free when first io_link_timeout_fn() puts linked timeout in the fail path, and then will be found and put on master's free.

Affected products

Linux kernel: from 5.11 before 5.12.10; 5.13-rc1 — fixed in 5.12.10

How to fix

Upgrade to a fixed version: Linux kernel 5.12.10. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/1f64f5e903b9d1d157875721e02adadc9d6f0a5d
https://git.kernel.org/stable/c/447c19f3b5074409c794b350b10306e1da1ef4ba
https://git.kernel.org/stable/c/1f64f5e903b9d1d157875721e02adadc9d6f0a5d
https://git.kernel.org/stable/c/447c19f3b5074409c794b350b10306e1da1ef4ba

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