CVE-2024-40935: cachefiles: flush all requests after setting CACHEFILES_DEAD

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-12 · updated 2026-06-17
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: cachefiles: flush all requests after setting CACHEFILES_DEAD In ondemand mode, when the daemon is processing an open request, if the kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write() will always return -EIO, so the daemon can't pass the copen to the kernel. Then the kernel process that is waiting for the copen triggers a hung_task. Since the DEAD state is irreversible, it can only be exited by closing /dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to avoid the above hungtask. We may still be able to read some of the cached data before closing the fd of /dev/cachefiles. Note that this relies on the patch that adds reference counting to the req, otherwise it may UAF.

Affected products

Linux kernel: from 5.19 before 6.1.95; from 6.2 before 6.6.35; from 6.7 before 6.9.6; 6.10-rc1, 6.10-rc2, 6.10-rc3 — fixed in 6.1.95, 6.6.35, 6.9.6

How to fix

Upgrade to a fixed version: Linux kernel 6.1.95, 6.6.35, 6.9.6. Check the vendor advisory for mitigations.

References

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