CVE-2024-42084: ftruncate: pass a signed offset

Severity: medium (CVSS 5.5 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: 2024-07-29 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: ftruncate: pass a signed offset The old ftruncate() syscall, using the 32-bit off_t misses a sign extension when called in compat mode on 64-bit architectures. As a result, passing a negative length accidentally succeeds in truncating to file size between 2GiB and 4GiB. Changing the type of the compat syscall to the signed compat_off_t changes the behavior so it instead returns -EINVAL. The native entry point, the truncate() syscall and the corresponding loff_t based variants are all correct already and do not suffer from this mistake.

Affected products

Linux kernel: from 3.9 before 4.19.317; from 4.20 before 5.4.279; from 5.5 before 5.10.221; from 5.11 before 5.15.162; from 5.16 before 6.1.97; from 6.2 before 6.6.37 — fixed in 4.19.317, 5.10.221, 5.15.162, 5.4.279, 6.1.97, 6.6.37

How to fix

Upgrade to a fixed version: Linux kernel 4.19.317, 5.10.221, 5.15.162, 5.4.279. Check the vendor advisory for mitigations.

References

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