kernel/git/stable/linux-stable.git/net/sched/act_ct.c, branch master

net/sched: add get_fill_size callbacks for actions missing them

2026-08-20T19:16:43+00:00

Several tc actions - act_police, act_bpf, act_pedit, act_ife, act_sample, act_ct, act_ctinfo and act_tunnel_key among them - provide no get_fill_size() callback, so tcf_action_fill_size() falls back to tcf_action_shared_attrs_size() which does not account for the action-specific netlink attributes emitted inside TCA_ACT_OPTIONS by their dump functions. When an RTM_NEWACTION request with NLM_F_ECHO (or an RTNLGRP_TC listener) creates several actions, tcf_add_notify_msg() allocates the echo skb from this underestimated size. When this happens, the act_api code fails to add all of the fields to the netlink message and, thus, fails to send it. Issue is that, when that happens, this failure doesn't stop the action instances from being added. So any user watching these events will be under the false impression that no actions were created at all. For example, act_pedit overruns with 32 actions of four munge keys each, act_police with 32 policers once the optional rate/peakrate/result/avrate attributes are present. To fix this, add the missing get_fill_size callbacks returning the worst-case size of each action's dump attributes, following the pattern used by act_gact/act_skbedit/act_vlan. Also widen the TCA_GACT_TM accounting in tcf_action_shared_attrs_size() to nla_total_size_64bit(), since actions dump their tcf_t with nla_put_64bit(), which may be preceded by an NLA_PAD attribute. Note: We only provided fixes for the actions we reproduced this bug with as of today. We can send a separate hardening patch for the remaining actions to net-next later. The other pre-existing issues, pointed out by Clashiko [1], will be fixed in upcoming patches. [1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260810164357.1653956-1-victor%40mojatatu.com Fixes: 4e76e75d6aba ("net sched actions: calculate add/delete event message size") Reported-by: Vega Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260816201327.2435335-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

Merge tag 'nf-next-26-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next

2026-08-14T19:23:12+00:00

Pablo Neira Ayuso says: ==================== Netfilter updates for net This includes an enhancement to detect ct memleaks easier via DEBUG_NET and flowtable preparation patches for IPv4 over IPV6 and vice-versa. This also includes a fix for the nft_ct custom expectation support. 1) Add DEBUG_NET_WARN_ON_ONCE to nf_ct_set() to spot ct memleaks. 2) Pass struct net_device_path_ctx to dev_fill_forward_path() to make it easier to pass more parameters to this function. From Lorenzo Bianconi. 3) Add ether_type field to net_device_path context structucture. 4) Rename tun.l3_proto field to tun.inner_proto. 5) Rename ctx.tun.proto to ctx.tun.inner_proto. 6) Store ether_type in flowtable context. 7) Move IPv4 and IPv6 xmit path to a helper function. 8) Move encapsulation header parser out of the flowtable lookup function. 9) Rework nft_ct custom expectation support to address a possible reallocation of ct extension area while expectation list also contains expectations. Move datapath to a ct helper to fix it. 10) Ensure timeout is always lowered for the non-closing RST case in the TCP connection tracking. 11) Bail out when inserting already dead expectation, this should not ever happen, hence report it via DEBUG_NET. 12) Comestic updates for improving the conntrack selftest dump and flush userspace program, from Qingshuang Fu. * tag 'nf-next-26-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next: selftests: netfilter: conntrack_dump_flush: remove unused variables and fix typo netfilter: nf_conntrack_expect: bail out on insert dead expectations netfilter: conntrack: always lower timeout for non-closing RST packets netfilter: nft_ct: move custom expectation support to helper netfilter: flowtable: detach layer 2 encapsulation parser from lookup netfilter: flowtable: move ipv4 and ipv6 xmit path to function netfilter: flowtable: store ethertype in flowtable context netfilter: flowtable: rename ctx.tun.proto to ctx.tun.inner_proto netfilter: flowtable: rename tun.l3_proto to tun.inner_proto net: netfilter: add ether_type to net_device_path_ctx and use it net: pass net_device_path_ctx to dev_fill_forward_path() netfilter: add DEBUG_NET_WARN_ON_ONCE to skb_set_nfct() ==================== Link: https://patch.msgid.link/20260810194015.932627-1-pablo@netfilter.org Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-08-13T18:00:14+00:00

Cross-merge networking fixes after downstream PR (net-7.2-rc8). No conflicts. Adjacent changes: drivers/net/ethernet/wangxun/ngbe/ngbe_main.c 5f3a13e0bb5e ("net: ngbe: fix NULL pointer dereference in non-MSI-X interrupt enabling") d661abdc30c2 ("net: ngbe: correct misleading interrupt comment") drivers/net/ipvlan/ipvlan_main.c e16e960d55a4 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev") 00a40d809207 ("ipvlan: Support per-netns netdev unregistration.") Signed-off-by: Jakub Kicinski

net/sched: act_ct: fix sk_buff leak when the header checks reject a packet

2026-08-10T23:37:07+00:00

tcf_ct_handle_fragments() runs its header sanity checks before handing anything to the defragmentation engine: if (family == NFPROTO_IPV4) err = tcf_ct_ipv4_is_fragment(skb, &frag); else err = tcf_ct_ipv6_is_fragment(skb, &frag); if (err || !frag) return err; tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM; tcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of them frees or queues the skb, so on that path the caller still owns it. tcf_ct_act() however funnels every non-zero return into the ownership-transfer exit: err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag); if (err) goto out_frag; ... out_frag: if (err != -EINPROGRESS) tcf_action_inc_drop_qstats(&c->common); return TC_ACT_CONSUMED; TC_ACT_CONSUMED means the action took ownership of the skb, so no caller frees it - sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for that verdict. The skb is therefore orphaned: one sk_buff plus its data buffer is leaked per malformed packet, unbounded. Note the drop counter is already incremented for these errors, so the statistics claim a drop that never happens. Three different ownership states reach out_frag: today - the skb may be queued by the defrag engine (-EINPROGRESS), already freed by nf_ct_handle_fragments(), or still owned by us. Tell the caller which of those it is, and free the packet ourselves in the last case, which restores the TC_ACT_SHOT behaviour that predated the Fixes: commit. Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6 header with nexthdr = 0 (hop-by-hop) and nothing after it, on a clsact ingress chain with "action ct". kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet; with this patch it reports none. Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") Cc: stable@vger.kernel.org # v6.8+ Signed-off-by: Hyunjung Ko Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260806101235.809370-1-hj351016@gmail.com Signed-off-by: Jakub Kicinski

netfilter: add DEBUG_NET_WARN_ON_ONCE to skb_set_nfct()

2026-08-10T11:01:37+00:00

Trigger a warning if nf_ct_set() overlaps an existing ct object leading to refcount leak. Add this warning to skb_set_nfct() whose only user is nf_ct_set() instead. Update existing nf_ct_set() callers to use nf_reset_ct() first to clean up stale pointer to conntrack object which migh trigger false positive warnings. Reviewed-by: Fernando Fernandez Mancera Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: get rid of tuple in helper definitions

2026-07-02T10:17:14+00:00

Leftover from the days when the kernel did automatic assignment of helpers based on a pre-registered / well-known-port. This helper autoassign was removed from the kernel, so all we really need are the l3 and l4 protocol numbers. In the broadcast helper, the only remaining consumer of the port number is removed. AFAICS its not needed: The expectation is populated from the control connection reply tuple, so the src port is the original directions destination (snmp/161 for example). LLM complained about silent l3num (u16) -> nfproto (u8) truncation, so add a netlink policy validation to reject large NFPROTO values upfront. Assisted-by: Claude:claude-sonnet-4-6 Signed-off-by: Florian Westphal

net/sched: act_ct: fix nf_connlabels leak on two error paths

2026-06-21T22:00:47+00:00

tcf_ct_fill_params() calls nf_connlabels_get() (setting put_labels) when TCA_CT_LABELS is present, but two later error sites use a bare return instead of "goto err", skipping the err: nf_connlabels_put() cleanup. They also precede the "p->put_labels = put_labels" assignment, so the tcf_ct_params_free() fallback does not release the count either. Each failed RTM_NEWACTION on these paths leaks one nf_connlabels reference: net->ct.labels_used is incremented and never released. The action is reachable with CAP_NET_ADMIN over the netns, i.e. from an unprivileged user namespace on default-userns kernels. Impact: an unprivileged user with CAP_NET_ADMIN over a network namespace (e.g. via user namespaces) leaks one nf_connlabels reference per failed RTM_NEWACTION on the two error paths; net->ct.labels_used is never released. The err: label is safe to reach from both sites: p->tmpl is still NULL there (kzalloc'd, not yet assigned) and nf_ct_put(NULL) is a no-op, so no inline release is needed. Fixes: 70f06c115bcc ("sched: act_ct: switch to per-action label counting") Signed-off-by: Michael Bommarito Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260617215708.1115818-1-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski

net/sched: act_ct: preserve tc_skb_cb across defragmentation

2026-06-19T00:38:51+00:00

tcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving and restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases the tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through act_ct therefore loses qdisc metadata such as pkt_segs and can trigger WARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled. Save and restore the full tc_skb_cb around nf_ct_handle_fragments(), matching the pattern used by ovs_ct_handle_fragments(). Fixes: ec624fe740b4 ("net/sched: Extend qdisc control block with tc control block") Cc: stable@vger.kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Zihan Xi Signed-off-by: Ren Wei Link: https://patch.msgid.link/510c51217fd7aaf29c6dc298bab8d643fe229b1c.1781358692.git.xizh2024@lzu.edu.cn Signed-off-by: Jakub Kicinski

net/sched: act_ct: Only release RCU read lock after ct_ft

2026-04-12T16:26:15+00:00

When looking up a flow table in act_ct in tcf_ct_flow_table_get(), rhashtable_lookup_fast() internally opens and closes an RCU read critical section before returning ct_ft. The tcf_ct_flow_table_cleanup_work() can complete before refcount_inc_not_zero() is invoked on the returned ct_ft resulting in a UAF on the already freed ct_ft object. This vulnerability can lead to privilege escalation. Analysis from zdi-disclosures@trendmicro.com: When initializing act_ct, tcf_ct_init() is called, which internally triggers tcf_ct_flow_table_get(). static int tcf_ct_flow_table_get(struct net *net, struct tcf_ct_params *params) { struct zones_ht_key key = { .net = net, .zone = params->zone }; struct tcf_ct_flow_table *ct_ft; int err = -ENOMEM; mutex_lock(&zones_mutex); ct_ft = rhashtable_lookup_fast(&zones_ht, &key, zones_params); // [1] if (ct_ft && refcount_inc_not_zero(&ct_ft->ref)) // [2] goto out_unlock; ... } static __always_inline void *rhashtable_lookup_fast( struct rhashtable *ht, const void *key, const struct rhashtable_params params) { void *obj; rcu_read_lock(); obj = rhashtable_lookup(ht, key, params); rcu_read_unlock(); return obj; } At [1], rhashtable_lookup_fast() looks up and returns the corresponding ct_ft from zones_ht . The lookup is performed within an RCU read critical section through rcu_read_lock() / rcu_read_unlock(), which prevents the object from being freed. However, at the point of function return, rcu_read_unlock() has already been called, and there is nothing preventing ct_ft from being freed before reaching refcount_inc_not_zero(&ct_ft->ref) at [2]. This interval becomes the race window, during which ct_ft can be freed. Free Process: tcf_ct_flow_table_put() is executed through the path tcf_ct_cleanup() call_rcu() tcf_ct_params_free_rcu() tcf_ct_params_free() tcf_ct_flow_table_put(). static void tcf_ct_flow_table_put(struct tcf_ct_flow_table *ct_ft) { if (refcount_dec_and_test(&ct_ft->ref)) { rhashtable_remove_fast(&zones_ht, &ct_ft->node, zones_params); INIT_RCU_WORK(&ct_ft->rwork, tcf_ct_flow_table_cleanup_work); // [3] queue_rcu_work(act_ct_wq, &ct_ft->rwork); } } At [3], tcf_ct_flow_table_cleanup_work() is scheduled as RCU work static void tcf_ct_flow_table_cleanup_work(struct work_struct *work) { struct tcf_ct_flow_table *ct_ft; struct flow_block *block; ct_ft = container_of(to_rcu_work(work), struct tcf_ct_flow_table, rwork); nf_flow_table_free(&ct_ft->nf_ft); block = &ct_ft->nf_ft.flow_block; down_write(&ct_ft->nf_ft.flow_block_lock); WARN_ON(!list_empty(&block->cb_list)); up_write(&ct_ft->nf_ft.flow_block_lock); kfree(ct_ft); // [4] module_put(THIS_MODULE); } tcf_ct_flow_table_cleanup_work() frees ct_ft at [4]. When this function executes between [1] and [2], UAF occurs. This race condition has a very short race window, making it generally difficult to trigger. Therefore, to trigger the vulnerability an msleep(100) was inserted after[1] Fixes: 138470a9b2cc2 ("net/sched: act_ct: fix lockdep splat in tcf_ct_flow_table_get") Reported-by: zdi-disclosures@trendmicro.com Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260410111627.46611-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

2026-02-28T03:06:21+00:00

As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/ Reported-by: GangMin Kim Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") CC: stable@vger.kernel.org Signed-off-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260225134349.1287037-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski