Description
In the Linux kernel, the following vulnerability has been resolved: net_sched: red: fix a race in __red_change() Gerrard Tai reported a race condition in RED, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.
Affected products
linux: linux kernel; debian: debian linux
References10
- git.kernel.org/stable/c/110a47efcf23438ff8d31dbd9c854fae2a48bf98 Patch
- git.kernel.org/stable/c/2790c4ec481be45a80948d059cd7c9a06bc37493 Patch
- git.kernel.org/stable/c/2a71924ca4af59ffc00f0444732b6cd54b153d0e Patch
- git.kernel.org/stable/c/444ad445df5496a785705019268a8a84b84484bb Patch
- git.kernel.org/stable/c/4b755305b2b0618e857fdadb499365b5f2e478d1 Patch
- git.kernel.org/stable/c/85a3e0ede38450ea3053b8c45d28cf55208409b8 Patch
- git.kernel.org/stable/c/a1bf6a4e9264a685b0e642994031f9c5aad72414 Patch
- git.kernel.org/stable/c/f569984417a4e12c67366e69bdcb752970de921d Patch
- lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing ListThird Party Advisory
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html Mailing ListThird Party Advisory
Metrics
- CVSS 3.1
-
7.0
HIGH
Score source: NVD
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 5 · as of 7 November 2026
- CWE
- CWE-362
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