Bug 2360926 (CVE-2025-38637)

Summary: CVE-2025-38637 kernel: net_sched: skbprio: Remove overly strict queue assertions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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OS: Linux   
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Description OSIDB Bzimport 2025-04-18 08:01:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net_sched: skbprio: Remove overly strict queue assertions

In the current implementation, skbprio enqueue/dequeue contains an assertion
that fails under certain conditions when SKBPRIO is used as a child qdisc under
TBF with specific parameters. The failure occurs because TBF sometimes peeks at
packets in the child qdisc without actually dequeuing them when tokens are
unavailable.

This peek operation creates a discrepancy between the parent and child qdisc
queue length counters. When TBF later receives a high-priority packet,
SKBPRIO's queue length may show a different value than what's reflected in its
internal priority queue tracking, triggering the assertion.

The fix removes this overly strict assertions in SKBPRIO, they are not
necessary at all.
Comment 1 Avinash Hanwate 2025-04-18 13:30:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025041819-CVE-2025-38637-8e27@gregkh/T