Description
In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: Fix qlen accounting bug when using peek in hfsc_enqueue() When enqueuing the first packet to an HFSC class, hfsc_enqueue() calls the child qdisc's peek() operation before incrementing sch->q.qlen and sch->qstats.backlog. If the child qdisc uses qdisc_peek_dequeued(), this may trigger an immediate dequeue and potential packet drop. In such cases, qdisc_tree_reduce_backlog() is called, but the HFSC qdisc's qlen and backlog have not yet been updated, leading to inconsistent queue accounting. This can leave an empty HFSC class in the active list, causing further consequences like use-after-free. This patch fixes the bug by moving the increment of sch->q.qlen and sch->qstats.backlog before the call to the child qdisc's peek() operation. This ensures that queue length and backlog are always accurate when packet drops or dequeues are triggered during the peek.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 1034e3310752e8675e313f7271b348914008719aaffected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < f9f593e34d2fb67644372c8f7b033bdc622ad228affected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 89c301e929a0db14ebd94b4d97764ce1d6981653affected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4affected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 93c276942e75de0e5bc91576300d292e968f5a02affected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 49b21795b8e5654a7df3d910a12e1060da4c04cfaffected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335affected12d0ad3be9c3854e52ec74bb83bb6f43612827c7 to < 3f981138109f63232a5fb7165938d4c945cc1b9daffected
Linux Linux
Default version status: affected
4.8affected0 to < 4.8unaffected5.4.294 to ≤ 5.4.*unaffected5.10.238 to ≤ 5.10.*unaffected5.15.185 to ≤ 5.15.*unaffected6.1.141 to ≤ 6.1.*unaffected6.6.93 to ≤ 6.6.*unaffected6.12.31 to ≤ 6.12.*unaffected6.14.9 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719a ↗
- https://git.kernel.org/stable/c/f9f593e34d2fb67644372c8f7b033bdc622ad228 ↗
- https://git.kernel.org/stable/c/89c301e929a0db14ebd94b4d97764ce1d6981653 ↗
- https://git.kernel.org/stable/c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4 ↗
- https://git.kernel.org/stable/c/93c276942e75de0e5bc91576300d292e968f5a02 ↗
- https://git.kernel.org/stable/c/49b21795b8e5654a7df3d910a12e1060da4c04cf ↗
- https://git.kernel.org/stable/c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335 ↗
- https://git.kernel.org/stable/c/3f981138109f63232a5fb7165938d4c945cc1b9d ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html ↗