kernel/linux.git/net/sched, branch v6.6.148

net/sched: act_tunnel_key: Defer dst_release to RCU callback

2026-08-03T09:15:16+00:00

[ Upstream commit f1f5c8a3955f8fda3f84ed883ac8daa1847e724c ] Fix a race-condition use-after-free in tunnel_key_release_params(). The function releases the metadata_dst of the old params synchronously via dst_release() while deferring the params struct free with kfree_rcu(). A concurrent tunnel_key_act() reader on the datapath may still hold the old params pointer (under rcu_read_lock_bh) and proceed to call dst_clone(¶ms->tcft_enc_metadata->dst) after the writer's dst_release has already pushed the dst's rcuref to RCUREF_DEAD. zdi-disclosures@trendmicro.com produced a poc which i (and Victor) verified that KASAN reports: ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 BUG: KASAN: slab-use-after-free in atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 BUG: KASAN: slab-use-after-free in __rcuref_put include/linux/rcuref.h:109 BUG: KASAN: slab-use-after-free in rcuref_put include/linux/rcuref.h:173 BUG: KASAN: slab-use-after-free in dst_release+0x5b/0x370 net/core/dst.c:168 Write of size 4 at addr ffff88806158de40 by task poc/9388 CPU: 0 UID: 0 PID: 9388 Comm: poc Tainted: G W 7.1.0-rc7 #7 PREEMPT(lazy) Tainted: [W]=WARN Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 print_report+0x139/0x4ad mm/kasan/report.c:482 kasan_report+0xe4/0x1d0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 kasan_check_range+0x125/0x200 mm/kasan/generic.c:200 instrument_atomic_read_write include/linux/instrumented.h:112 atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 __rcuref_put include/linux/rcuref.h:109 rcuref_put include/linux/rcuref.h:173 dst_release+0x5b/0x370 net/core/dst.c:168 refdst_drop include/net/dst.h:272 skb_dst_drop include/net/dst.h:284 skb_release_head_state+0x293/0x400 net/core/skbuff.c:1163 skb_release_all net/core/skbuff.c:1187 [..] Allocated by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 __kasan_kmalloc+0x9a/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 __do_kmalloc_node mm/slub.c:5296 __kmalloc_noprof+0x2f1/0x830 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 kzalloc_noprof include/linux/slab.h:1188 offload_action_alloc+0x2f/0x130 net/core/flow_offload.c:35 tcf_action_offload_add_ex+0x1ba/0x880 net/sched/act_api.c:258 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 [..] Freed by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 __kasan_slab_free+0x6b/0x90 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 slab_free_hook mm/slub.c:2689 slab_free mm/slub.c:6251 kfree+0x21f/0x6b0 mm/slub.c:6566 tcf_action_offload_add_ex+0x4ad/0x880 net/sched/act_api.c:284 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 The buggy address belongs to the object at ffff88806158de00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 64 bytes inside of freed 256-byte region [ffff88806158de00, ffff88806158df00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806158d600 pfn:0x6158c head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x4fff00000000240(workingset|head|node=1|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 04fff00000000240 ffff88801c841b40 ffffea0001856290 ffffea0001856190 raw: ffff88806158d600 0000000800100009 00000000f5000000 0000000000000000 head: 04fff00000000240 ffff88801c841b40 ffffea0001856290 ffffea0001856190 head: ffff88806158d600 0000000800100009 00000000f5000000 0000000000000000 head: 04fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 9391, tgid 9378 (poc), ts 123227323196, free_ts 0 set_page_owner include/linux/page_owner.h:32 post_alloc_hook+0xfe/0x140 mm/page_alloc.c:1853 prep_new_page mm/page_alloc.c:1861 get_page_from_freelist+0x110c/0x2fc0 mm/page_alloc.c:3941 __alloc_frozen_pages_noprof+0x263/0x2bc0 mm/page_alloc.c:5221 alloc_slab_page mm/slub.c:3278 allocate_slab mm/slub.c:3467 new_slab+0xa6/0x690 mm/slub.c:3525 refill_objects+0x271/0x420 mm/slub.c:7272 refill_sheaf mm/slub.c:2816 __pcs_replace_empty_main+0x373/0x630 mm/slub.c:4652 alloc_from_pcs mm/slub.c:4750 slab_alloc_node mm/slub.c:4884 __do_kmalloc_node mm/slub.c:5295 __kmalloc_noprof+0x66d/0x830 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 metadata_dst_alloc+0x26/0x90 net/core/dst.c:298 tun_rx_dst include/net/dst_metadata.h:144 __ip_tun_set_dst include/net/dst_metadata.h:208 tunnel_key_init+0xb01/0x1b90 net/sched/act_tunnel_key.c:451 tcf_action_init_1+0x46b/0x6c0 net/sched/act_api.c:1428 tcf_action_init+0x448/0xa20 net/sched/act_api.c:1503 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 [..] ================================================================== Fix by moving dst_release() into a custom RCU callback that runs after the grace period, matching the lifetime of the containing params struct. Readers in the datapath therefore always find a live rcuref when calling dst_clone(). Fixes: 9174c3df1cd18 ("net/sched: act_tunnel_key: fix memory leak in case of action replace") Reported-by: zdi-disclosures@trendmicro.com Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Reviewed-by: Davide Caratti Link: https://patch.msgid.link/20260711150537.7946-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: sch_taprio: Replace direct dequeue call with peek and qdisc_dequeue_peeked

2026-07-24T14:03:43+00:00

commit e056e1dfcddca877dd46d704e8ec9860cfc9ec44 upstream. When taprio's software path peeks a non-work-conserving child qdisc, the child stashes the peeked skb in its gso_skb; taprio_dequeue_from_txq() then takes the packet with a direct child ->dequeue() call, which ignores that stash, orphans the peeked skb and desyncs the child's qlen/backlog. With a qfq child this re-enters the child on an emptied list and dereferences NULL, panicking the kernel from softirq on ordinary egress. Take the packet through qdisc_dequeue_peeked(), as sch_red and sch_sfb now do. The helper returns the child's stashed skb first and is a no-op when there is none, so a work-conserving child is unaffected and the gated path now consumes the skb whose length was charged to the budget. Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler") Cc: stable@vger.kernel.org Cc: Vladimir Oltean Signed-off-by: Bryam Vargas Reviewed-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260625-b4-disp-31bcb279-v1-1-85c40b83c529@proton.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sched: sch_multiq: Replace direct dequeue call with peek and qdisc_dequeue_peeked

2026-07-24T14:03:43+00:00

commit 54f6b0c843e228d499eb4b6bbb89df68cad9ad5d upstream. multiq_dequeue() takes a packet from a band's child with a direct ->dequeue() call after multiq_peek() peeked it. When the child is non-work-conserving the peek stashes the skb in the child's gso_skb, so the direct dequeue returns a different skb and orphans the stash, desyncing the child's qlen/backlog. With a qfq child reached through a peeking parent (e.g. tbf) this re-enters the child on an emptied list and dereferences NULL, panicking the kernel from softirq on ordinary egress. Take the packet through qdisc_dequeue_peeked(), as sch_prio already does and as sch_red and sch_sfb were just fixed to do. The helper is a no-op when the child has no stash, so a work-conserving child is unaffected. Fixes: 77be155cba4e ("pkt_sched: Add peek emulation for non-work-conserving qdiscs.") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260625-b4-disp-31bcb279-v1-2-85c40b83c529@proton.me Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sched: sch_teql: move rcu_read_lock()/spin_lock() from _bh variants

2026-07-24T14:03:42+00:00

commit 6301f6a34ed86fe6f3b7b3211ea069f3677fc559 upstream. This is a followup based on sashiko comments [1] on commit e5b811fe7931 ("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF") Use plain rcu_read_lock()/spin_lock() in teql_master_xmit() instead of the _bh variants, since ndo_start_xmit is already invoked with BH disabled by the core stack and the _bh primitives can warn in_hardirq() when xmit is reached through netpoll or a softirq xmit path with hard IRQs disabled. Moves rcu_read_lock() after restart: label + adds rcu_read_unlock() before goto restart (fixes the unbounded RCU hold across retries) [1] https://sashiko.dev/#/patchset/20260628111229.669751-1-jhs%40mojatatu.com Signed-off-by: Jamal Hadi Salim Fixes: e5b811fe7931 ("net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF") Link: https://patch.msgid.link/20260630150922.238714-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

net/sched: act_ct: preserve tc_skb_cb across defragmentation

2026-07-24T14:03:42+00:00

commit 9092e15defbe6c7bc241c306093ca9d358a578e7 upstream. 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 Signed-off-by: Greg Kroah-Hartman

net/sched: cake: reject overhead values that underflow length

2026-07-24T14:03:28+00:00

[ Upstream commit b7f97cae7ec1b6c3c32843c42be218690d310467 ] CAKE accepts signed overhead values and stores them in an s16, but the adjusted packet length calculation uses unsigned arithmetic. A negative effective length can therefore wrap to a large value. Such configurations make rate accounting depend on integer wraparound rather than on the packet size userspace intended to model. A static netlink lower bound is not enough because packets reaching CAKE can be smaller than any reasonable manual-overhead allowance. Fold the signed overhead adjustment into the existing datapath MPU clamp so negative adjusted lengths are clamped before link-layer framing adjustments. Fixes: a729b7f0bd5b ("sch_cake: Add overhead compensation support to the rate shaper") Assisted-by: Codex:gpt-5.5-cyber-preview Signed-off-by: Samuel Moelius Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260702000758.297407.e5c888d9d99d.cake-overhead-underflow@trailofbits.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload

2026-07-24T14:03:27+00:00

[ Upstream commit 8b519cbcabe836a441369fbec1a8a6518a709251 ] There is a TOCTOU race condition in flower lockless approach between sizing a flow_rule buffer and filling it. zdi-disclosures@trendmicro.com reports: The cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED (fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the independent locking domains make the race reachable in practice. KASAN confirms: BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930 Write of size 4 at addr ffff888001f27520 by task poc-toctou/312 The buggy address is located 0 bytes to the right of allocated 288-byte region [ffff888001f27400, ffff888001f27520) (cache kmalloc-512) Note: The result is a heap OOB write attacker-controlled content into the adjacent slab object (requires CAP_NET_ADMIN). The fix introduces reading tcfp_nkeys under act->tcfa_lock in all places using a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys(). Additionally we close the remaining TOCTOU window between the sizing read and the fill reads by more careful accounting. Rather than silently truncating the key count, which leads to incorrect action semantics offloaded to hardware and secondary OOB writes if the remaining capacity is zero or consumed by prior actions, we enforce remaining capacity checks and return -ENOSPC if the required space exceeds the remaining capacity. Fixes: 71d0ed7079df ("net/act_pedit: Support using offset relative to the conventional network headers") Reported-by: zdi-disclosures@trendmicro.com Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260701161912.125355-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: hhf: clear heavy-hitter state on reset

2026-07-24T14:03:25+00:00

[ Upstream commit a225f8c20712713406ae47024b8df42deacddd4a ] HHF reset does not clear the classifier state used to identify heavy hitters. Packets after reset can therefore be scheduled using flow history from before the reset. The reset operation should return the qdisc to an empty state. Clear the heavy-hitter classifier tables when HHF is reset. Fixes: 10239edf86f1 ("net-qdisc-hhf: Heavy-Hitter Filter (HHF) qdisc") Assisted-by: Codex:gpt-5.5-cyber-preview Signed-off-by: Samuel Moelius Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net/sched: act_bpf: use rcu_dereference_bh() to read the filter

2026-07-24T14:03:25+00:00

[ Upstream commit adc49c7ba690c9b33b8392ec27397456b65d0893 ] tcf_bpf_act() can run from the tc egress path, which holds only rcu_read_lock_bh(), but reads prog->filter with rcu_dereference() and trips lockdep: WARNING: suspicious RCU usage net/sched/act_bpf.c:47 suspicious rcu_dereference_check() usage! 1 lock held by syz.2.1588/12756: #0: (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit net/core/dev.c:4792 tcf_bpf_act+0x6ae/0x940 net/sched/act_bpf.c:47 tcf_classify+0x6e4/0x1080 net/sched/cls_api.c:1860 sch_handle_egress net/core/dev.c:4545 [inline] __dev_queue_xmit+0x2185/0x2c00 net/core/dev.c:4808 packet_sendmsg+0x3dfa/0x5120 net/packet/af_packet.c:3114 The other tc actions and cls_bpf already use rcu_dereference_bh() here. Do the same. Fixes: 1f211a1b929c ("net, sched: add clsact qdisc") Signed-off-by: Sechang Lim Reviewed-by: Amery Hung Link: https://patch.msgid.link/20260629154112.1164986-1-rhkrqnwk98@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF

2026-07-24T14:03:25+00:00

[ Upstream commit e5b811fe793166aecc59b085c1b7c31262ef2316 ] The teql master->slaves singly linked list is not protected against multiple writes. It can be mod'ed concurently from teql_master_xmit(), teql_dequeue(), teql_init() and teql_destroy() without holding any list lock or RCU protection. zdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed after an RCU grace period, but teql_master_xmit() running on another CPU can still hold a stale pointer into the list, resulting in a slab-use-after-free: BUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f/0x16b0 Read of size 8 at addr ffff888013fb0440 by task poc/332 Freed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512) The fix? Add a per-master slaves_lock spinlock that serializes all mutations of master->slaves and the NEXT_SLAVE() links in teql_destroy() and teql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock around those updates. Annotate master->slaves and the per-slave ->next pointer with __rcu and use the appropriate RCU accessors everywhere they are touched: rcu_assign_pointer() on the writer side (under slaves_lock), rcu_dereference_protected() for the writer-side loads (also under slaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and rtnl_dereference() for the loads in teql_master_open()/teql_master_mtu(), which run under RTNL. Pair this with rcu_read_lock_bh()/rcu_read_unlock_bh() around the list traversal in teql_master_xmit(), so that readers either observe a fully linked list or are deferred until the in-flight mutation completes. The two early-return paths in teql_master_xmit() are updated to release the RCU-bh read-side critical section before returning, since leaving it held would disable BH on that CPU for good. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: zdi-disclosures@trendmicro.com Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260628111229.669751-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin