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CVE-2026-90072

net/sched: sfq: clamp quantum to avoid signed overflow soft lockup

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: sfq: clamp quantum to avoid signed overflow soft lockup sfq_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) (unsigned). A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000, so slot->allot = INT_MIN and INT_MIN + INT_MIN toggles between INT_MIN and 0 forever, spinning sfq_dequeue() under the qdisc lock. Clamp the quantum to [256, 1 << 20] so the refill loop terminates. The lower bound also covers q->quantum == 0 (psched_mtu() returning 0), which spins sfq_dequeue() identically. sfq_change() already rejects a negative quantum, so only the init path was exposed. Conditions to recreate the bug: a device whose MTU (plus hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 86799499585af06a9431c9e7782658667bd62650; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 2017c355a5a1af77736cd1739fe922f69b5652dc; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 6581a82bf08ba5d4e2a6d4e3080df43315b296c4; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 9d782c662879c3adaaca30e05c36910ad11b9e54; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in d72dbdfaeb5b9b8d884e0e036c3442754379ef74; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in aeb8196ecb95146e3410f635628e6cd47352b3e5; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in da16c31517cd2c06bb2c78c73e91ae192c01c426; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 816e90057ab1879562a5b7cc688e35bb9027ae97

  • Linux Linux

    2.6.12

  • KernelLinux

    From 2.6.12 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6

References 8

git.kernel.org