netfilter: nf_conntrack_expect: use conntrack GC to reap expectations

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80668
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 08:16:52 UTC
Updated2026-08-28 08:16:52 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_expect: use conntrack GC to reap expectations This patch replaces the timer API by GC worker approach for expectations, as it already happened in many other subsystems. Use the existing conntrack GC worker to iterate over the local list of expectations in the master conntrack to reap expired expectations. Check IPS_HELPER_BIT to run GC for expectations, set it on for nft_ct expectation which nevers sets it. Hold the expectation spinlock while iterating over the master conntrack expectation list to synchronize with nf_ct_remove_expectations(). This also performs runtime packet path garbage collection through the expectation insertion and lookup functions while walking over one of the chains of the global expectation hashtables. Unconfirmed conntrack entries are skipped since ct->ext can be reallocated and dying are skipped since those will be gone soon. Set on IPS_HELPER_BIT if the helper ct extension is added, then the new GC worker does not need to bump the ct refcount to check if the ct->ext helper is available. This removes the extra bump on the refcount for expectation timers, this allows to remove several nf_ct_expect_put() calls after the unlink, after this update only refcount remains at 1 while on the expectation hashes. This patch implicitly addresses a race with the existing timer API allowing an expectation to access a stale exp->master pointer which has been already released when expectation removal loses races with an expiring timer, ie. timer_del() reporting false. Add a new NF_CT_EXPECT_DEAD flag to reap this expectation via GC. This is needed by nf_conntrack_unexpect_related() which is called in error paths to invalidate newly created expectations that has been added into the hashes. These expectactions cannot be inmediately released as GC or nf_ct_remove_expectations() could race to make it. On expectation insert, the runtime GC reaps stale expectations before checking the expectation limit set by policy. Set current timestamp in nf_ct_expect_alloc(), then add the expectation policy timeout (or custom timeout specified added on top of this) to specify the expectation lifetime.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5 7ec786f4230c2a9b2eaf97a2d45368933b49d2b2 git Not specified
CNA Linux Linux affected bffcaad9afdfe45d7fc777397d3b83c1e3ebffe5 b8b09dc2bf35a00d4e0556b5d6308c7b917ebda2 git Not specified
CNA Linux Linux affected 9e1196d27ef496f404c76f7a9d03761142d991c4 git Not specified
CNA Linux Linux affected 5e1c1d22268ae710c238342c8030c21daf298168 git Not specified
CNA Linux Linux affected d52fa1fa7440676b8c238037a050ab008c22737f git Not specified
CNA Linux Linux affected f338ced0473849c9f6ed0b77ca99f1aab5826787 git Not specified
CNA Linux Linux affected 497f99b26fffdc5635706d1b4811f1ed8ee21a5b git Not specified
CNA Linux Linux affected 6.1.176 6.2 semver Not specified
CNA Linux Linux affected 6.6.143 6.7 semver Not specified
CNA Linux Linux affected 6.12.94 6.13 semver Not specified
CNA Linux Linux affected 6.18.24 6.19 semver Not specified
CNA Linux Linux affected 6.19.14 6.20 semver Not specified
CNA Linux Linux affected 7.0 Not specified
CNA Linux Linux unaffected 7.0 semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b8b09dc2bf35a00d4e0556b5d6308c7b917ebda2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7ec786f4230c2a9b2eaf97a2d45368933b49d2b2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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