CVE-2022-48828: NFSD: Fix ia_size underflow

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-16 · updated 2026-10-14
Weakness: CWE-191

Description

In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix ia_size underflow iattr::ia_size is a loff_t, which is a signed 64-bit type. NFSv3 and NFSv4 both define file size as an unsigned 64-bit type. Thus there is a range of valid file size values an NFS client can send that is already larger than Linux can handle. Currently decode_fattr4() dumps a full u64 value into ia_size. If that value happens to be larger than S64_MAX, then ia_size underflows. I'm about to fix up the NFSv3 behavior as well, so let's catch the underflow in the common code path: nfsd_setattr().

Affected products

Linux kernel: before 5.4.295; from 5.5 before 5.10.220; from 5.11 before 5.15.24; from 5.16 before 5.16.10; 5.17-rc1, 5.17-rc2, 5.17-rc3 — fixed in 5.10.220, 5.15.24, 5.16.10, 5.4.295

How to fix

Upgrade to a fixed version: Linux kernel 5.10.220, 5.15.24, 5.16.10, 5.4.295. Check the vendor advisory for mitigations.

References

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