CVE-2024-38580: epoll: be better about file lifetimes

Severity: medium (CVSS 4.7 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: 2024-06-19 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: epoll: be better about file lifetimes epoll can call out to vfs_poll() with a file pointer that may race with the last 'fput()'. That would make f_count go down to zero, and while the ep->mtx locking means that the resulting file pointer tear-down will be blocked until the poll returns, it means that f_count is already dead, and any use of it won't actually get a reference to the file any more: it's dead regardless. Make sure we have a valid ref on the file pointer before we call down to vfs_poll() from the epoll routines.

Affected products

Linux kernel: before 5.15.161; from 5.16 before 6.1.93; from 6.2 before 6.6.33; from 6.7 before 6.8.12; 6.9-rc1, 6.9-rc2, 6.9-rc3, 6.9-rc4, 6.9-rc5, 6.9-rc6 — fixed in 5.15.161, 6.1.93, 6.6.33, 6.8.12

How to fix

Upgrade to a fixed version: Linux kernel 5.15.161, 6.1.93, 6.6.33, 6.8.12. Check the vendor advisory for mitigations.

References

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