Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: fq: add overflow bounds to quantum and initial quantum fq_init() computes quantum = 2 * psched_mtu() and initial_quantum = 10 * psched_mtu() with no overflow check. A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000; the 2 * and 10 * multiplications wrap to 0 in 32-bit arithmetic, so q->quantum == 0. Then in fq_dequeue() the credit-refill loop adds 0 to f->credit (which stays <= 0) and goto begin loops forever under the qdisc lock, creating a soft lockup. Clamp psched_mtu() to [1, 1 << 20] before multiplying so the product cannot wrap, then cap the result at 1 << 20, matching the bound already enforced on TCA_FQ_QUANTUM in fq_change(). Conditions to recreate the bug: a device whose MTU (plus hard_header_len) is large enough that 2 * psched_mtu() wraps (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.
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
afe4fd062416b158a8a8538b23adc1930a9b88dc to < cf398f67d9caa71af3b9fb9319058b22fe6b524eaffectedafe4fd062416b158a8a8538b23adc1930a9b88dc to < fd63409b669f9951f1cc6b02486a5254103800d1affectedafe4fd062416b158a8a8538b23adc1930a9b88dc to < d16dac3925be95ad46e986d4b139c9898b6e227faffectedafe4fd062416b158a8a8538b23adc1930a9b88dc to < f6b3e3848a5fca63438984acd6d9eceac80814c1affectedafe4fd062416b158a8a8538b23adc1930a9b88dc to < e35acd56f244d94355f9ab237c2ecc8fba5e6f04affectedafe4fd062416b158a8a8538b23adc1930a9b88dc to < 709f34f7c28dc4dd6c40343d101850f11e172312affected
Linux Linux
Default version status: affected
3.12affected0 to < 3.12unaffected6.1.191 to ≤ 6.1.*unaffected6.6.160 to ≤ 6.6.*unaffected6.12.110 to ≤ 6.12.*unaffected6.18.52 to ≤ 6.18.*unaffected7.2.6 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/cf398f67d9caa71af3b9fb9319058b22fe6b524e ↗
- https://git.kernel.org/stable/c/fd63409b669f9951f1cc6b02486a5254103800d1 ↗
- https://git.kernel.org/stable/c/d16dac3925be95ad46e986d4b139c9898b6e227f ↗
- https://git.kernel.org/stable/c/f6b3e3848a5fca63438984acd6d9eceac80814c1 ↗
- https://git.kernel.org/stable/c/e35acd56f244d94355f9ab237c2ecc8fba5e6f04 ↗
- https://git.kernel.org/stable/c/709f34f7c28dc4dd6c40343d101850f11e172312 ↗