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CVE-2026-97958

net/sched: cls_api: Don't replay RTM_GETCHAIN in tc_ctl_chain(). PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: Don't replay RTM_GETCHAIN in tc_ctl_chain(). If a netlink socket sends RTM_GETCHAIN requests repeatedly without recv()ing the responses, tc_ctl_chain() hogs CPU and triggers Hung Task splat. [0] As caught in the stack trace, netlink_attachskb() could confuse tc_ctl_chain() by returning -EAGAIN when the userspace netlink socket's receive buffer is full. The replay: label exists since commit 32a4f5ecd738 ("net: sched: introduce chain object to uapi") but was not used initially. Since commit 9f407f1768d3 ("net: sched: introduce chain templates"), the label is needed for RTM_NEWCHAIN because tcf_proto_lookup_ops() may release RTNL to call request_module(). However, the replay logic is unnecessary for RTM_GETCHAIN. Let's apply the replay logic only for RTM_NEWCHAIN. [0]: INFO: task repro:1018 is blocked on a mutex likely owned by task repro:1022. task:repro state:R running task stack:14096 pid:1022 tgid:1014 ppid:961 task_flags:0x400040 flags:0x00080000 Call Trace: <TASK> ? clockevents_program_event (kernel/time/clockevents.c:372) ? pskb_expand_head (net/core/skbuff.c:615) ? skb_release_data (net/core/skbuff.c:1122) ? netlink_attachskb (./include/linux/skbuff.h:1323 ./include/linux/skbuff.h:1332 net/netlink/af_netlink.c:1232) ? __netlink_lookup (./include/linux/rcupdate.h:882 ./include/linux/rhashtable.h:711 net/netlink/af_netlink.c:499) ? tc_chain_notify (net/sched/cls_api.c:3045) ? tc_chain_notify (./include/linux/skbuff.h:1384 net/sched/cls_api.c:3041) ? netlink_unicast (net/netlink/af_netlink.c:1335) ? rtnl_unicast (./include/net/netlink.h:1198 net/core/rtnetlink.c:985) ? tc_ctl_chain (net/sched/cls_api.c:3242) ? rtnetlink_rcv_msg (net/core/rtnetlink.c:7146) ? netlink_unicast (net/netlink/af_netlink.c:1354) ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:7177) ? netlink_rcv_skb (net/netlink/af_netlink.c:2556) ? netlink_unicast (net/netlink/af_netlink.c:1319) ? netlink_sendmsg (net/netlink/af_netlink.c:1900) ? __sock_sendmsg (net/socket.c:800) ? __sys_sendto (net/socket.c:2281) ? __x64_sys_sendto (net/socket.c:2288 net/socket.c:2284 net/socket.c:2284) ? do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84) ? entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) </TASK>

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before 240251a4ca7cda213103694b6e21c4a5745e5d8b; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before 9a0f07f7dbd1bfe8c2fd03ad055e9e60a703d5df; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before 6558b0d46c5941ed1aa67da8878e224c54239cc5; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before 96c2fc5daf983af2e0c1256c31e89c1f3f855279; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before a1c2840d95af1fa3d83ba71e23fa0c674a4c6796; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before 503ba58481e3ba69d28127d35a39cec529f9670c; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before e9ac395bb56122a057d0aa91a6b55d9e3fa37c26; affected 2ed9db3074fcd8d12709fe40ff0e691d74229818 before dff39930ad5e53d202bfdfb14687d1d2fd753b4d
Linux / Linuxaffected 4.19; unaffected 0 before 4.19; unaffected 5.10.271 through 5.10.*; unaffected 5.15.222 through 5.15.*; unaffected 6.1.189 through 6.1.*; unaffected 6.6.158 through 6.6.*; unaffected 6.12.111 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References