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| author | Jamal Hadi Salim <jhs@mojatatu.com> | 2026-09-01 17:39:28 -0400 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-09-05 13:48:08 -0700 |
| commit | 8382abec0f1568d0a5590d75a3df92f23fcf5196 (patch) | |
| tree | fe77f0017dcac841cc996d880c30b641ef9c32d7 /scripts/basic | |
| parent | 54370e44c002770ae61fc889f28f699e91616ffc (diff) | |
| download | linux-8382abec0f1568d0a5590d75a3df92f23fcf5196.tar.gz linux-8382abec0f1568d0a5590d75a3df92f23fcf5196.zip | |
net/sched: drr: clamp quantum in change class
drr_change_class() rejects explicit quantum==0 but falls back to
psched_mtu() with no floor. With a crafted size table qdisc_pkt_len
reaches ~2 GiB, so quantum=1 (or a zero psched_mtu on a headerless
device) makes the deficit-refill loop spin under the qdisc lock.
Add clamp_t(u32, quantum, 256, 1<<20) after the zero reject and on the
fallback path. The explicit-zero reject is preserved.
Conditions to recreate the bug:
CONFIG_NET_SCH_DRR=y. Requires CAP_NET_ADMIN (namespace-local via
unshare -Urn suffices).
tc qdisc add dev dummy0 root drr
tc class add dev dummy0 parent 1: classid 1:1 drr quantum 1
Fixes: 13d2a1d2b032 ("pkt_sched: add DRR scheduler")
Reported-by: Vega <vega@nebusec.ai>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/QDISC-0CFC.v3.20260901204856@mojatatu.com.8
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'scripts/basic')
0 files changed, 0 insertions, 0 deletions