net/sched: hhf: cap hh_flows_limit at change time

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98234
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 09:18:11 UTC
Updated2026-10-06 09:18:11 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: hhf: cap hh_flows_limit at change time hhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge hh_flows_limit lets each new heavy-hitter flow pass the hh_flows_current_cnt check in alloc_new_hh() and forces a fixed-size kzalloc(GFP_ATOMIC) per flow under spoofed traffic, for unbounded memory growth. Bound the attribute with NLA_POLICY_MAX() at 2*HH_FLOWS_CNT (the hhf_init() default) and report the rejected value via extack. The deprecated nested parse is kept: legacy tc does not set NLA_F_NESTED on TCA_OPTIONS. Configs relying on hh_limit above the default were relying on unbounded, unsafe behaviour and are not supported going forward. hhf_init() also ran hhf_change() before setting the default hh_flows_limit, so a user-supplied hh_limit at add time was clobbered back to 2048. Set the default before hhf_change() so the configured value sticks. This is a follow-up to commit eb56a495f59b ("net/sched: hhf: clamp quantum in change and init paths"), which bounded the quantum of the same qdisc; the hh_flows_limit bound is the remaining unbounded knob of that series' scope. Conditions to recreate the bug: CAP_NET_ADMIN in a user namespace; tc qdisc change dev X root hhf hh_limit 4294967295 succeeds and the value is echoed by tc qdisc show, unbounding heavy-hitter flow allocations; also tc qdisc add dev X root hhf hh_limit 500 stores 2048 instead of 500.

Risk And Classification

EPSS: 0.002200000 probability, percentile 0.113620000 (date 2026-10-06)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 7adfd0a42174b85c6bd678858ecd6674f403f336 git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 35fd423a5c5132c6f4321f6c4f0a7b4b90af830c git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 06d2a101e89063cb0b9b459104db48bdfb0a797d git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 d8e2f1f0263b7c97b222c06070cccf13e0ab7112 git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4 git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 1731ff1d20489afe4cd01b7d16d37f324746ac54 git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 f6547d27ce2093c5627636fb63dd0b7523c466f9 git Not specified
CNA Linux Linux affected 10239edf86f137ce4c39b62ea9575e8053c549a0 2cef2588c995722a901368def30befeef9ae55c6 git Not specified
CNA Linux Linux affected 3.14 Not specified
CNA Linux Linux unaffected 3.14 semver Not specified
CNA Linux Linux unaffected 5.10.271 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.222 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.189 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.158 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.54 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.8 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc4 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/f6547d27ce2093c5627636fb63dd0b7523c466f9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/35fd423a5c5132c6f4321f6c4f0a7b4b90af830c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7adfd0a42174b85c6bd678858ecd6674f403f336 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/06d2a101e89063cb0b9b459104db48bdfb0a797d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1731ff1d20489afe4cd01b7d16d37f324746ac54 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2cef2588c995722a901368def30befeef9ae55c6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d8e2f1f0263b7c97b222c06070cccf13e0ab7112 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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