kernel/linux.git/net/sched, branch v7.1.8

net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds

2026-08-09T18:26:31+00:00

[ Upstream commit aef96eead2860cbfa371e4471d4f04412213b958 ] u32_change() copies the user-provided tc_u32_sel.offshift (unsigned char, 0-255) into the kernel knode object without bounds validation. When a packet later hits u32_classify() with TC_U32_VAROFFSET set, it evaluates `ntohs(offmask & *data) >> offshift` where the left operand is a 16-bit value promoted to a 32-bit int. Any offshift >= 32 is undefined behavior per C11 6.5.7p3, triggerable by an unprivileged user via user/network namespaces. UBSAN: shift-out-of-bounds in net/sched/cls_u32.c:236:43 shift exponent 32 is too large for 32-bit type int Fix this by rejecting offshift >= 16 during filter creation in u32_change(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: AutonomousCodeSecurity@microsoft.com Link: https://lore.kernel.org/all/20260720034514.23053-1-blbllhy@gmail.com Signed-off-by: Cen Zhang (Microsoft) Acked-by: Jamal Hadi Salim Tested-by: Jamal Hadi Salim Tested-by: Victor Nogueira Link: https://patch.msgid.link/20260723044955.89471-1-blbllhy@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: sch_cake: skip clearing unused tins during rate adjustment

2026-08-09T18:26:28+00:00

[ Upstream commit a3729e0df005a936ceb3c2b0d167f01a2b03f970 ] When cake_configure_rates() is called from the dequeue path with rate_adjust=true, it only needs to update the rate parameters. The loop that clears the unused tins is both unnecessary and harmful in this path: - cake_clear_tin() overwrites q->cur_tin and q->cur_flow, which are actively used by cake_dequeue(), corrupting the dequeue state. - iterating over the unused tins and their internal queues to purge packets adds needless overhead to the hot path. Skip the entire loop when rate_adjust is set, as neither cake_clear_tin() nor the mtu_time update are needed when only the rate changes. The clearing loop runs on every rate adjustment from the dequeue path, clearing (max_tins - cur_tins) tins each time, so the cost grows the fewer tins the configured mode actually uses. Testing cake_mq over veth (8 rx/tx queues, 2 Gbit limit) with flent's [1] rrul and tcp_nup tests and 32 TCP upstreams shows a large drop in loaded latency and a throughput gain, restoring behaviour to pre-15c2715a5264 levels: +------------+------+------+-------+-------+---------+ | kernel | mode | test | base | load | tput | | | | | (ms) | (ms) | (Mbit) | +------------+------+------+-------+-------+---------+ | net-next | be | rrul | 0.810 | 11.78 | 1469.67 | | net-next | be | nup | 0.637 | 85.71 | 1243.15 | | net-next | ds3 | rrul | 0.397 | 15.28 | 1770.06 | | net-next | ds3 | nup | 0.351 | 15.98 | 1799.39 | +------------+------+------+-------+-------+---------+ | patched | be | rrul | 0.092 | 0.56 | 1873.40 | | patched | be | nup | 0.109 | 1.82 | 1869.12 | | patched | ds3 | rrul | 0.097 | 0.98 | 1866.10 | | patched | ds3 | nup | 0.101 | 0.51 | 1861.79 | +------------+------+------+-------+-------+---------+ The same trend holds on real hardware (IPQ8074A, 4 rx/tx queues, OpenWrt): in besteffort mode the tcp_nup loaded latency drops from ~470 ms to ~4 ms. [1] https://flent.org Fixes: 15c2715a5264 ("net/sched: sch_cake: fixup cake_mq rate adjustment for diffserv config") Signed-off-by: Jonas Köppeler Tested-by: Mike Pham Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260720-sch_cake-skip-clearing-tins-v2-1-e6a8b0275c73@tu-berlin.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: serialize qdisc_rtab_list against concurrent get/put

2026-08-03T09:25:58+00:00

commit f43ee0c0730d6191629b5ee1ceae27b1ebfdc047 upstream. qdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly linked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no lock. This was only safe because every caller historically held the RTNL mutex, which serialized all rate-table lookups, inserts and frees. That invariant no longer holds. cls_flower sets TCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false for it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through tcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() -> tcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the RTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each adding a flower filter with a police action carrying the same rate, then race on qdisc_rtab_list and on the non-atomic refcnt, leading to a use-after-free / double-free of the kmalloc-2k struct qdisc_rate_table. qdisc_rtab_list is a single global (not per-netns), so the corrupted object is shared system-wide. BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160 qdisc_put_rtab+0x12f/0x160 tcf_police_init+0xda9/0x1590 tcf_action_init_1+0x460/0x6b0 tcf_action_init+0x439/0xa40 tcf_exts_validate_ex+0x42d/0x550 fl_change+0xddd/0x7da0 tc_new_tfilter+0xaa7/0x2420 rtnetlink_rcv_msg+0x95e/0xe90 which belongs to the cache kmalloc-2k of size 2048 Protect qdisc_rtab_list and the refcount with a dedicated spinlock. The (sleeping, GFP_KERNEL) allocation in qdisc_get_rtab() is performed before taking the lock; if a concurrent inserter added an identical table in the meantime the freshly allocated one is freed under the lock, so no duplicate is leaked. qdisc_put_rtab() now decrements the refcount and unlinks under the same lock. Fixes: 470502de5bdb ("net: sched: unlock rules update API") Suggested-by: Eric Dumazet Signed-off-by: Aldo Ariel Panzardo Cc: stable@vger.kernel.org Acked-by: Jamal Hadi Salim Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260715114114.446841-1-qwe.aldo@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains

2026-08-03T09:25:30+00:00

[ Upstream commit ec48b3be2c8595dd290be883dbd4fb8b2f9f5d5e ] When a TC filter attached to a qdisc filter chain returns TC_ACT_REDIRECT (ex: via an eBPF program calling bpf_redirect() or an act_bpf action), the redirect was silently lost i.e no qdisc classify function handled TC_ACT_REDIRECT, so the packet fell through the switch and was enqueued normally instead of being redirected. This has been broken since bpf_redirect() was introduced for TC in commit 27b29f63058d ("bpf: add bpf_redirect() helper"). We got lucky for a long time because bpf_net_context was a per-CPU variable that was always available. commit 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") turned bpf_net_context into a task_struct member that is only set up by explicit callers. Without a caller setting it up, bpf_redirect() itself crashes with a NULL pointer dereference in bpf_net_ctx_get_ri(). However, even with bpf_net_context available, TC_ACT_REDIRECT from qdisc filter chains cannot be honored without adding skb_do_redirect() calls to every qdisc classify function, which would require changes across net/sched/. Isolate it to ebpf core where it belongs. Instead, add a tcf_classify_qdisc() inline helper in pkt_cls.h, as a wrapper around tcf_classify() for use by qdisc classify functions and tcf_qevent_handle(). When the classify verdict is TC_ACT_REDIRECT, the wrapper converts it to TC_ACT_SHOT, dropping the packet rather than letting it continue silently. Dropping is preferred over letting the packet through because the user immediately sees packet loss. Silently passing the packet through would hide the problem and leave the user wondering why their redirect is not working. The clsact fast path, tc_run() continues to call tcf_classify() directly and is unaffected: TC_ACT_REDIRECT is returned as-is and handled by sch_handle_egress/ingress() calling skb_do_redirect() as before. Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper") Fixes: 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Signed-off-by: Daniel Borkmann Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260706185609.330006-3-daniel@iogearbox.net Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

bpf: Reject redirect helpers without a bpf_net_context

2026-08-03T09:25:30+00:00

[ Upstream commit 3f4920d165b29052255527d8ae7619e7ec132ece ] The bpf_redirect*() helpers and skb_do_redirect() obtain the per-task bpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the current->bpf_net_context unconditionally. That context is established on the paths that run tc BPF such as sch_handle_{ingress,egress}(), *except* for the case where {cls,act}_bpf was attached to a proper qdisc. A program running from there reaches the NULL deref in two ways: * It calls bpf_redirect() directly, which dereferences the context at the top of the helper: tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \ avpkt 1000 burst 100 qevent early_drop block 10 tc filter add block 10 pref 1 bpf obj redirect.o * It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle() then dispatches to skb_do_redirect(), which dereferences the context Rather than extending bpf_net_context management into the qdisc path, make the redirect helpers refuse to operate when no context exists, and have tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of calling skb_do_redirect(). Previous behaviour was a crash, so nothing regresses by not supporting it. Fixes: 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Fixes: 3625750f05ec ("net: sched: Introduce helpers for qevent blocks") Signed-off-by: Daniel Borkmann Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260706185609.330006-2-daniel@iogearbox.net Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: act_tunnel_key: Defer dst_release to RCU callback

2026-08-03T09:25:23+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

2026-07-24T14:21:18+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

2026-07-24T14:21:18+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

2026-07-24T14:21:16+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

2026-07-24T14:21:15+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