net/sched: sch_qfq: Fix race condition on qfq_aggregate

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix race condition on qfq_aggregate A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.

Timeline

1. Jul 28, 2025, 11:21 AM UTCCVE published
2. Jun 10, 2026, 8:41 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 15, 2026, 1:07 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in aa7a22c4d678bf649fd3a1d27debec583563414d; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in d841aa5518508ab195b6781ad0d73ee378d713dd; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in c6df794000147a3a02f79984aada4ce83f8d0a1e; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in 466e10194ab81caa2ee6a332d33ba16bcceeeba6; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in fbe48f06e64134dfeafa89ad23387f66ebca3527; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in a6d735100f602c830c16d69fb6d780eebd8c9ae1; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in c000a3a330d97f6c073ace5aa5faf94b9adb4b79; From 462dbc9101acd38e92eda93c0726857517a24bbd · fixed in 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64

• Linux Linux

  3.8

• KernelLinux

  From 3.8.0 · fixed in 5.4.297; From 5.5.0 · fixed in 5.10.241; From 5.11.0 · fixed in 5.15.190; From 5.16.0 · fixed in 6.1.147; From 6.2.0 · fixed in 6.6.100; From 6.7.0 · fixed in 6.12.40; From 6.13.0 · fixed in 6.15.8

References 8