net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-90109
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:02 UTC
Updated2026-09-17 17:17:02 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue gred_enqueue(), bfifo_enqueue() and plug_enqueue() admit a packet when the current backlog plus the packet length fits within the queue limit: sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (gred default VQ) gred_backlog+qdisc_pkt_len(skb) <= q->limit (gred configured VQ) sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (bfifo) sch->qstats.backlog + skb->len <= q->limit (plug) sch->qstats.backlog and q->backlog are u32, and qdisc_pkt_len()/skb->len are unsigned int, so all sums are computed in 32 bits and wrap at 2^32. Once the true backlog exceeds 4 GiB the wrapped sum becomes small and admission keeps succeeding, so the queue grows without bound and the kernel can be driven to OOM. Promote the sums to u64 so admission stops once the true backlog exceeds the limit. The limit is u32, so the bounded queue stays below 2^32 and the stored u32 backlog never wraps. The bug can only be reproduced as root (albeit with ridiculous setup): attach a gred (or bfifo/plug) qdisc with a limit near 4 GiB, leaving the default VQ unconfigured (for gred), and drive >4 GiB of queued traffic (e.g. via a size table / stab to inflate qdisc_pkt_len, or sustained high-rate traffic). The u32 backlog+len sum wraps at 2^32, admission keeps succeeding, and the queue grows unboundedly to OOM.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 3fb51b3960342bbee563543f8d33710fd0fb5a96 git Not specified
CNA Linux Linux affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6 git Not specified
CNA Linux Linux affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 d98b92f3d57976ae185238946ec5ea0be32195aa git Not specified
CNA Linux Linux affected a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 4c660ee8c809637909f4f7eb1017f7b9401c75c4 git Not specified
CNA Linux Linux affected 4.2 Not specified
CNA Linux Linux unaffected 4.2 semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d98b92f3d57976ae185238946ec5ea0be32195aa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4c660ee8c809637909f4f7eb1017f7b9401c75c4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3fb51b3960342bbee563543f8d33710fd0fb5a96 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

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report