CVE-2026-23413 (GCVE-0-2026-23413)
Vulnerability from cvelistv5
Published
2026-04-02 11:40
Modified
2026-10-19 18:35
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: clsact: Fix use-after-free in init/destroy rollback asymmetry Fix a use-after-free in the clsact qdisc upon init/destroy rollback asymmetry. The latter is achieved by first fully initializing a clsact instance, and then in a second step having a replacement failure for the new clsact qdisc instance. clsact_init() initializes ingress first and then takes care of the egress part. This can fail midway, for example, via tcf_block_get_ext(). Upon failure, the kernel will trigger the clsact_destroy() callback. Commit 1cb6f0bae504 ("bpf: Fix too early release of tcx_entry") details the way how the transition is happening. If tcf_block_get_ext on the q->ingress_block ends up failing, we took the tcx_miniq_inc reference count on the ingress side, but not yet on the egress side. clsact_destroy() tests whether the {ingress,egress}_entry was non-NULL. However, even in midway failure on the replacement, both are in fact non-NULL with a valid egress_entry from the previous clsact instance. What we really need to test for is whether the qdisc instance-specific ingress or egress side previously got initialized. This adds a small helper for checking the miniq initialization called mini_qdisc_pair_inited, and utilizes that upon clsact_destroy() in order to fix the use-after-free scenario. Convert the ingress_destroy() side as well so both are consistent to each other.
References
Impacted products
Vendor Product Version
Linux Linux Version: 230bb13650b0f186f540500fd5f5f7096a822a2a
Version: 1cb6f0bae50441f4b4b32a28315853b279c7404e
Version: 1cb6f0bae50441f4b4b32a28315853b279c7404e
Version: 1cb6f0bae50441f4b4b32a28315853b279c7404e
Version: 1cb6f0bae50441f4b4b32a28315853b279c7404e
Version: f61ecf1bd5b562ebfd7d430ccb31619857e80857
Version: 6.6.41   ≤
Version: 6.9.10   ≤
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