{"id":"CVE-2026-97958","summary":"net/sched: cls_api: Don't replay RTM_GETCHAIN in tc_ctl_chain().","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: Don't replay RTM_GETCHAIN in tc_ctl_chain().\n\nIf a netlink socket sends RTM_GETCHAIN requests repeatedly\nwithout recv()ing the responses, tc_ctl_chain() hogs CPU and\ntriggers Hung Task splat. [0]\n\nAs caught in the stack trace, netlink_attachskb() could confuse\ntc_ctl_chain() by returning -EAGAIN when the userspace netlink\nsocket's receive buffer is full.\n\nThe replay: label exists since commit 32a4f5ecd738 (\"net: sched:\nintroduce chain object to uapi\") but was not used initially.\n\nSince commit 9f407f1768d3 (\"net: sched: introduce chain templates\"),\nthe label is needed for RTM_NEWCHAIN because tcf_proto_lookup_ops()\nmay release RTNL to call request_module().\n\nHowever, the replay logic is unnecessary for RTM_GETCHAIN.\n\nLet's apply the replay logic only for RTM_NEWCHAIN.\n\n[0]:\nINFO: task repro:1018 is blocked on a mutex likely owned by task repro:1022.\ntask:repro           state:R  running task     stack:14096 pid:1022  tgid:1014  ppid:961    task_flags:0x400040 flags:0x00080000\nCall Trace:\n \u003cTASK\u003e\n ? clockevents_program_event (kernel/time/clockevents.c:372)\n ? pskb_expand_head (net/core/skbuff.c:615)\n ? skb_release_data (net/core/skbuff.c:1122)\n ? netlink_attachskb (./include/linux/skbuff.h:1323 ./include/linux/skbuff.h:1332 net/netlink/af_netlink.c:1232)\n ? __netlink_lookup (./include/linux/rcupdate.h:882 ./include/linux/rhashtable.h:711 net/netlink/af_netlink.c:499)\n ? tc_chain_notify (net/sched/cls_api.c:3045)\n ? tc_chain_notify (./include/linux/skbuff.h:1384 net/sched/cls_api.c:3041)\n ? netlink_unicast (net/netlink/af_netlink.c:1335)\n ? rtnl_unicast (./include/net/netlink.h:1198 net/core/rtnetlink.c:985)\n ? tc_ctl_chain (net/sched/cls_api.c:3242)\n ? rtnetlink_rcv_msg (net/core/rtnetlink.c:7146)\n ? netlink_unicast (net/netlink/af_netlink.c:1354)\n ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:7177)\n ? netlink_rcv_skb (net/netlink/af_netlink.c:2556)\n ? netlink_unicast (net/netlink/af_netlink.c:1319)\n ? netlink_sendmsg (net/netlink/af_netlink.c:1900)\n ? __sock_sendmsg (net/socket.c:800)\n ? __sys_sendto (net/socket.c:2281)\n ? __x64_sys_sendto (net/socket.c:2288 net/socket.c:2284 net/socket.c:2284)\n ? do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84)\n ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n \u003c/TASK\u003e","modified":"2026-09-26T03:48:27.927949298Z","published":"2026-09-25T10:23:03.753Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97958.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/503ba58481e3ba69d28127d35a39cec529f9670c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a1c2840d95af1fa3d83ba71e23fa0c674a4c6796"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dff39930ad5e53d202bfdfb14687d1d2fd753b4d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e9ac395bb56122a057d0aa91a6b55d9e3fa37c26"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97958.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97958"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2ed9db3074fcd8d12709fe40ff0e691d74229818"},{"fixed":"a1c2840d95af1fa3d83ba71e23fa0c674a4c6796"},{"fixed":"503ba58481e3ba69d28127d35a39cec529f9670c"},{"fixed":"e9ac395bb56122a057d0aa91a6b55d9e3fa37c26"},{"fixed":"dff39930ad5e53d202bfdfb14687d1d2fd753b4d"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97958.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.19.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97958.json"}}],"schema_version":"1.9.0"}