CVE-2022-48809: net: fix a memleak when uncloning an skb dst and its metadata

Severity: medium (CVSS 5.5 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: 2024-07-16 · updated 2026-06-17
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: net: fix a memleak when uncloning an skb dst and its metadata When uncloning an skb dst and its associated metadata, a new dst+metadata is allocated and later replaces the old one in the skb. This is helpful to have a non-shared dst+metadata attached to a specific skb. The issue is the uncloned dst+metadata is initialized with a refcount of 1, which is increased to 2 before attaching it to the skb. When tun_dst_unclone returns, the dst+metadata is only referenced from a single place (the skb) while its refcount is 2. Its refcount will never drop to 0 (when the skb is consumed), leading to a memory leak. Fix this by removing the call to dst_hold in tun_dst_unclone, as the dst+metadata refcount is already 1.

Affected products

Linux kernel: from 4.3 before 4.9.302; from 4.10 before 4.14.267; from 4.15 before 4.19.230; from 4.20 before 5.4.180; from 5.5 before 5.10.101; from 5.11 before 5.15.24 — fixed in 4.14.267, 4.19.230, 4.9.302, 5.10.101, 5.15.24, 5.16.10

How to fix

Upgrade to a fixed version: Linux kernel 4.14.267, 4.19.230, 4.9.302, 5.10.101. Check the vendor advisory for mitigations.

References

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