Bug 2516682 (CVE-2026-72035)

Summary: CVE-2026-72035 kernel: net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's taprio (Time-Aware Priority Shaper) scheduler. When the taprio software path processes network packets from a non-work-conserving child queue discipline (qdisc), it can incorrectly handle the packet buffer, leading to a null pointer dereference. This issue can cause a kernel panic during ordinary network egress operations, resulting in a Denial of Service (DoS) for the system.
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Description OSIDB Bzimport 2026-08-15 06:25:36 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked

When taprio's software path peeks a non-work-conserving child qdisc, the
child stashes the peeked skb in its gso_skb; taprio_dequeue_from_txq()
then takes the packet with a direct child ->dequeue() call, which ignores
that stash, orphans the peeked skb and desyncs the child's qlen/backlog.
With a qfq child this re-enters the child on an emptied list and
dereferences NULL, panicking the kernel from softirq on ordinary egress.

Take the packet through qdisc_dequeue_peeked(), as sch_red and sch_sfb
now do. The helper returns the child's stashed skb first and is a no-op
when there is none, so a work-conserving child is unaffected and the
gated path now consumes the skb whose length was charged to the budget.
Comment 1 Keith Grant 2026-08-17 17:12:06 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081512-CVE-2026-72035-65da@gregkh/T