clsact: Fix use-after-free in init/destroy rollback asymmetry

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Summary

CVECVE-2026-23413
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-02 12:16:20 UTC
Updated2026-04-03 16:10:52 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.000180000 probability, percentile 0.046140000 (date 2026-04-07)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 230bb13650b0f186f540500fd5f5f7096a822a2a a73d95b57bf9faebdfed591bcb7ed9292062a84c git Not specified
CNA Linux Linux affected 1cb6f0bae50441f4b4b32a28315853b279c7404e 37bef86e5428d59f70a4da82b80f9a8f252fecbe git Not specified
CNA Linux Linux affected 1cb6f0bae50441f4b4b32a28315853b279c7404e 4c9af67f99aa3e51b522c54968ab3ac8272be41c git Not specified
CNA Linux Linux affected 1cb6f0bae50441f4b4b32a28315853b279c7404e 0509b762bc5e8ea7b8391130730c6d8502fc6e69 git Not specified
CNA Linux Linux affected 1cb6f0bae50441f4b4b32a28315853b279c7404e a0671125d4f55e1e98d9bde8a0b671941987e208 git Not specified
CNA Linux Linux affected f61ecf1bd5b562ebfd7d430ccb31619857e80857 git Not specified
CNA Linux Linux affected 6.10 Not specified
CNA Linux Linux unaffected 6.10 semver Not specified
CNA Linux Linux unaffected 6.6.130 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.78 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.20 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.10 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/4c9af67f99aa3e51b522c54968ab3ac8272be41c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0509b762bc5e8ea7b8391130730c6d8502fc6e69 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a0671125d4f55e1e98d9bde8a0b671941987e208 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/37bef86e5428d59f70a4da82b80f9a8f252fecbe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a73d95b57bf9faebdfed591bcb7ed9292062a84c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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