CVE-2025-38108 Information

Jul 04, 2025 cve

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.

Reference

https://git.kernel.org/stable/c/110a47efcf23438ff8d31dbd9c854fae2a48bf98 https://git.kernel.org/stable/c/2790c4ec481be45a80948d059cd7c9a06bc37493 https://git.kernel.org/stable/c/2a71924ca4af59ffc00f0444732b6cd54b153d0e https://git.kernel.org/stable/c/444ad445df5496a785705019268a8a84b84484bb https://git.kernel.org/stable/c/4b755305b2b0618e857fdadb499365b5f2e478d1 https://git.kernel.org/stable/c/85a3e0ede38450ea3053b8c45d28cf55208409b8 https://git.kernel.org/stable/c/a1bf6a4e9264a685b0e642994031f9c5aad72414 https://git.kernel.org/stable/c/f569984417a4e12c67366e69bdcb752970de921d

CNNVD-202507-194 (Published: 2025-07-03)

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