inet: frags: flush pending skbs in fqdir_pre_exit()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-68768
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-13 16:15:56 UTC
Updated2026-06-19 13:16:24 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: inet: frags: flush pending skbs in fqdir_pre_exit() We have been seeing occasional deadlocks on pernet_ops_rwsem since September in NIPA. The stuck task was usually modprobe (often loading a driver like ipvlan), trying to take the lock as a Writer. lockdep does not track readers for rwsems so the read wasn't obvious from the reports. On closer inspection the Reader holding the lock was conntrack looping forever in nf_conntrack_cleanup_net_list(). Based on past experience with occasional NIPA crashes I looked thru the tests which run before the crash and noticed that the crash follows ip_defrag.sh. An immediate red flag. Scouring thru (de)fragmentation queues reveals skbs sitting around, holding conntrack references. The problem is that since conntrack depends on nf_defrag_ipv6, nf_defrag_ipv6 will load first. Since nf_defrag_ipv6 loads first its netns exit hooks run _after_ conntrack's netns exit hook. Flush all fragment queue SKBs during fqdir_pre_exit() to release conntrack references before conntrack cleanup runs. Also flush the queues in timer expiry handlers when they discover fqdir->dead is set, in case packet sneaks in while we're running the pre_exit flush. The commit under Fixes is not exactly the culprit, but I think previously the timer firing would eventually unblock the spinning conntrack.

Risk And Classification

EPSS: 0.001680000 probability, percentile 0.063520000 (date 2026-06-24)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db 22ee4010866da81aeee08e1ea3fddbe418feb212 git Not specified
CNA Linux Linux affected d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db 543555954b1ee8d1903a7020324efb41b0c97428 git Not specified
CNA Linux Linux affected d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db c70df25214ac9b32b53e18e6ae3b8f073ffa6903 git Not specified
CNA Linux Linux affected d5dd88794a13c2f24cce31abad7a0a6c5e0ed2db 006a5035b495dec008805df249f92c22c89c3d2e git Not specified
CNA Linux Linux affected 5.3 Not specified
CNA Linux Linux unaffected 5.3 semver Not specified
CNA Linux Linux unaffected 6.6.143 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.93 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.3 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c70df25214ac9b32b53e18e6ae3b8f073ffa6903 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/543555954b1ee8d1903a7020324efb41b0c97428 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/006a5035b495dec008805df249f92c22c89c3d2e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/22ee4010866da81aeee08e1ea3fddbe418feb212 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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