{"id":"CVE-2026-98234","published":"2026-10-06T09:18:11.033","lastModified":"2026-10-06T09:18:11.033","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: cap hh_flows_limit at change time\n\nhhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge\nhh_flows_limit lets each new heavy-hitter flow pass the\nhh_flows_current_cnt check in alloc_new_hh() and forces a fixed-size\nkzalloc(GFP_ATOMIC) per flow under spoofed traffic, for unbounded memory\ngrowth.\n\nBound the attribute with NLA_POLICY_MAX() at 2*HH_FLOWS_CNT (the\nhhf_init() default) and report the rejected value via extack. The\ndeprecated nested parse is kept: legacy tc does not set NLA_F_NESTED on\nTCA_OPTIONS. Configs relying on hh_limit above the default were relying\non unbounded, unsafe behaviour and are not supported going forward.\n\nhhf_init() also ran hhf_change() before setting the default\nhh_flows_limit, so a user-supplied hh_limit at add time was clobbered\nback to 2048. Set the default before hhf_change() so the configured\nvalue sticks.\n\nThis is a follow-up to commit eb56a495f59b (\"net/sched: hhf: clamp\nquantum in change and init paths\"), which bounded the quantum of the\nsame qdisc; the hh_flows_limit bound is the remaining unbounded knob of\nthat series' scope.\n\nConditions to recreate the bug: CAP_NET_ADMIN in a user namespace;\ntc qdisc change dev X root hhf hh_limit 4294967295 succeeds and the\nvalue is echoed by tc qdisc show, unbounding heavy-hitter flow\nallocations; also tc qdisc add dev X root hhf hh_limit 500 stores 2048\ninstead of 500.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/06d2a101e89063cb0b9b459104db48bdfb0a797d","tags":[]},{"url":"https://git.kernel.org/stable/c/1731ff1d20489afe4cd01b7d16d37f324746ac54","tags":[]},{"url":"https://git.kernel.org/stable/c/2cef2588c995722a901368def30befeef9ae55c6","tags":[]},{"url":"https://git.kernel.org/stable/c/35fd423a5c5132c6f4321f6c4f0a7b4b90af830c","tags":[]},{"url":"https://git.kernel.org/stable/c/7adfd0a42174b85c6bd678858ecd6674f403f336","tags":[]},{"url":"https://git.kernel.org/stable/c/d8e2f1f0263b7c97b222c06070cccf13e0ab7112","tags":[]},{"url":"https://git.kernel.org/stable/c/f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4","tags":[]},{"url":"https://git.kernel.org/stable/c/f6547d27ce2093c5627636fb63dd0b7523c466f9","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}