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

net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains

2026-07-21T01:16:43+00:00

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

net/sched: sch_ets: make cl->quantum lockless

2026-05-25T18:09:27+00:00

cl->quantum does not need to be protected by RTNL or qdisc spinlock. Signed-off-by: Eric Dumazet Reviewed-by: Victor Nogueira Link: https://patch.msgid.link/20260522110356.1403343-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: annotate data-races around sch->qstats.backlog

2026-05-12T01:28:07+00:00

Add qstats_backlog_sub() and qstats_backlog_add() helpers and use them instead of open-coding them. These helpers use WRITE_ONCE() to prevent store-tearing. Also use WRITE_ONCE() in fq_reset() and qdisc_reset() when sch->qstats.backlog is cleared. Signed-off-by: Eric Dumazet Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260510091455.4039245-4-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: add qdisc_qlen_inc() and qdisc_qlen_dec()

2026-05-12T01:28:07+00:00

Helpers to increment or decrement sch->q.qlen, with appropriate WRITE_ONCE() to prevent store tearing. Add other WRITE_ONCE() when sch->q.qlen is changed. Signed-off-by: Eric Dumazet Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260510091455.4039245-3-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: ets: fix divide by zero in the offload path

2026-02-27T02:28:47+00:00

Offloading ETS requires computing each class' WRR weight: this is done by averaging over the sums of quanta as 'q_sum' and 'q_psum'. Using unsigned int, the same integer size as the individual DRR quanta, can overflow and even cause division by zero, like it happened in the following splat: Oops: divide error: 0000 [#1] SMP PTI CPU: 13 UID: 0 PID: 487 Comm: tc Tainted: G E 6.19.0-virtme #45 PREEMPT(full) Tainted: [E]=UNSIGNED_MODULE Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets] Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44 RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246 RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660 RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000 FS: 00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0 Call Trace: ets_qdisc_change+0x870/0xf40 [sch_ets] qdisc_create+0x12b/0x540 tc_modify_qdisc+0x6d7/0xbd0 rtnetlink_rcv_msg+0x168/0x6b0 netlink_rcv_skb+0x5c/0x110 netlink_unicast+0x1d6/0x2b0 netlink_sendmsg+0x22e/0x470 ____sys_sendmsg+0x38a/0x3c0 ___sys_sendmsg+0x99/0xe0 __sys_sendmsg+0x8a/0xf0 do_syscall_64+0x111/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f440b81c77e Code: 4d 89 d8 e8 d4 bc 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff951e4c10 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000481820 RCX: 00007f440b81c77e RDX: 0000000000000000 RSI: 00007fff951e4cd0 RDI: 0000000000000003 RBP: 00007fff951e4c20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff951f4fa8 R13: 00000000699ddede R14: 00007f440bb01000 R15: 0000000000486980 Modules linked in: sch_ets(E) netdevsim(E) ---[ end trace 0000000000000000 ]--- RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets] Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44 RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246 RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660 RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000 FS: 00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0 Kernel panic - not syncing: Fatal exception Kernel Offset: 0x30000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception ]--- Fix this using 64-bit integers for 'q_sum' and 'q_psum'. Cc: stable@vger.kernel.org Fixes: d35eb52bd2ac ("net: sch_ets: Make the ETS qdisc offloadable") Signed-off-by: Davide Caratti Reviewed-by: Jamal Hadi Salim Reviewed-by: Petr Machata Link: https://patch.msgid.link/28504887df314588c7255e9911769c36f751edee.1771964872.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski

net/sched: ets: Remove drr class from the active list if it changes to strict

2025-12-11T09:36:40+00:00

Whenever a user issues an ets qdisc change command, transforming a drr class into a strict one, the ets code isn't checking whether that class was in the active list and removing it. This means that, if a user changes a strict class (which was in the active list) back to a drr one, that class will be added twice to the active list [1]. Doing so with the following commands: tc qdisc add dev lo root handle 1: ets bands 2 strict 1 tc qdisc add dev lo parent 1:2 handle 20: \ tbf rate 8bit burst 100b latency 1s tc filter add dev lo parent 1: basic classid 1:2 ping -c1 -W0.01 -s 56 127.0.0.1 tc qdisc change dev lo root handle 1: ets bands 2 strict 2 tc qdisc change dev lo root handle 1: ets bands 2 strict 1 ping -c1 -W0.01 -s 56 127.0.0.1 Will trigger the following splat with list debug turned on: [ 59.279014][ T365] ------------[ cut here ]------------ [ 59.279452][ T365] list_add double add: new=ffff88801d60e350, prev=ffff88801d60e350, next=ffff88801d60e2c0. [ 59.280153][ T365] WARNING: CPU: 3 PID: 365 at lib/list_debug.c:35 __list_add_valid_or_report+0x17f/0x220 [ 59.280860][ T365] Modules linked in: [ 59.281165][ T365] CPU: 3 UID: 0 PID: 365 Comm: tc Not tainted 6.18.0-rc7-00105-g7e9f13163c13-dirty #239 PREEMPT(voluntary) [ 59.281977][ T365] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 59.282391][ T365] RIP: 0010:__list_add_valid_or_report+0x17f/0x220 [ 59.282842][ T365] Code: 89 c6 e8 d4 b7 0d ff 90 0f 0b 90 90 31 c0 e9 31 ff ff ff 90 48 c7 c7 e0 a0 22 9f 48 89 f2 48 89 c1 4c 89 c6 e8 b2 b7 0d ff 90 <0f> 0b 90 90 31 c0 e9 0f ff ff ff 48 89 f7 48 89 44 24 10 4c 89 44 ... [ 59.288812][ T365] Call Trace: [ 59.289056][ T365] [ 59.289224][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.289546][ T365] ets_qdisc_change+0xd2b/0x1e80 [ 59.289891][ T365] ? __lock_acquire+0x7e7/0x1be0 [ 59.290223][ T365] ? __pfx_ets_qdisc_change+0x10/0x10 [ 59.290546][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.290898][ T365] ? __mutex_trylock_common+0xda/0x240 [ 59.291228][ T365] ? __pfx___mutex_trylock_common+0x10/0x10 [ 59.291655][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.291993][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.292313][ T365] ? trace_contention_end+0xc8/0x110 [ 59.292656][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.293022][ T365] ? srso_alias_return_thunk+0x5/0xfbef5 [ 59.293351][ T365] tc_modify_qdisc+0x63a/0x1cf0 Fix this by always checking and removing an ets class from the active list when changing it to strict. [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/tree/net/sched/sch_ets.c?id=ce052b9402e461a9aded599f5b47e76bc727f7de#n663 Fixes: cd9b50adc6bb9 ("net/sched: ets: fix crash when flipping from 'strict' to 'quantum'") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Reviewed-by: Petr Machata Link: https://patch.msgid.link/20251208190125.1868423-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change

2025-12-04T10:43:45+00:00

zdi-disclosures@trendmicro.com says: The vulnerability is a race condition between `ets_qdisc_dequeue` and `ets_qdisc_change`. It leads to UAF on `struct Qdisc` object. Attacker requires the capability to create new user and network namespace in order to trigger the bug. See my additional commentary at the end of the analysis. Analysis: static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt, struct netlink_ext_ack *extack) { ... // (1) this lock is preventing .change handler (`ets_qdisc_change`) //to race with .dequeue handler (`ets_qdisc_dequeue`) sch_tree_lock(sch); for (i = nbands; i < oldbands; i++) { if (i >= q->nstrict && q->classes[i].qdisc->q.qlen) list_del_init(&q->classes[i].alist); qdisc_purge_queue(q->classes[i].qdisc); } WRITE_ONCE(q->nbands, nbands); for (i = nstrict; i < q->nstrict; i++) { if (q->classes[i].qdisc->q.qlen) { // (2) the class is added to the q->active list_add_tail(&q->classes[i].alist, &q->active); q->classes[i].deficit = quanta[i]; } } WRITE_ONCE(q->nstrict, nstrict); memcpy(q->prio2band, priomap, sizeof(priomap)); for (i = 0; i < q->nbands; i++) WRITE_ONCE(q->classes[i].quantum, quanta[i]); for (i = oldbands; i < q->nbands; i++) { q->classes[i].qdisc = queues[i]; if (q->classes[i].qdisc != &noop_qdisc) qdisc_hash_add(q->classes[i].qdisc, true); } // (3) the qdisc is unlocked, now dequeue can be called in parallel // to the rest of .change handler sch_tree_unlock(sch); ets_offload_change(sch); for (i = q->nbands; i < oldbands; i++) { // (4) we're reducing the refcount for our class's qdisc and // freeing it qdisc_put(q->classes[i].qdisc); // (5) If we call .dequeue between (4) and (5), we will have // a strong UAF and we can control RIP q->classes[i].qdisc = NULL; WRITE_ONCE(q->classes[i].quantum, 0); q->classes[i].deficit = 0; gnet_stats_basic_sync_init(&q->classes[i].bstats); memset(&q->classes[i].qstats, 0, sizeof(q->classes[i].qstats)); } return 0; } Comment: This happens because some of the classes have their qdiscs assigned to NULL, but remain in the active list. This commit fixes this issue by always removing the class from the active list before deleting and freeing its associated qdisc Reproducer Steps (trimmed version of what was sent by zdi-disclosures@trendmicro.com) ``` DEV="${DEV:-lo}" ROOT_HANDLE="${ROOT_HANDLE:-1:}" BAND2_HANDLE="${BAND2_HANDLE:-20:}" # child under 1:2 PING_BYTES="${PING_BYTES:-48}" PING_COUNT="${PING_COUNT:-200000}" PING_DST="${PING_DST:-127.0.0.1}" SLOW_TBF_RATE="${SLOW_TBF_RATE:-8bit}" SLOW_TBF_BURST="${SLOW_TBF_BURST:-100b}" SLOW_TBF_LAT="${SLOW_TBF_LAT:-1s}" cleanup() { tc qdisc del dev "$DEV" root 2>/dev/null } trap cleanup EXIT ip link set "$DEV" up tc qdisc del dev "$DEV" root 2>/dev/null || true tc qdisc add dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2 tc qdisc add dev "$DEV" parent 1:2 handle "$BAND2_HANDLE" \ tbf rate "$SLOW_TBF_RATE" burst "$SLOW_TBF_BURST" latency "$SLOW_TBF_LAT" tc filter add dev "$DEV" parent 1: protocol all prio 1 u32 match u32 0 0 flowid 1:2 tc -s qdisc ls dev $DEV ping -I "$DEV" -f -c "$PING_COUNT" -s "$PING_BYTES" -W 0.001 "$PING_DST" \ >/dev/null 2>&1 & tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 0 tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2 tc -s qdisc ls dev $DEV tc qdisc del dev "$DEV" parent 1:2 || true tc -s qdisc ls dev $DEV tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 1 strict 1 ``` KASAN report ``` ================================================================== BUG: KASAN: slab-use-after-free in ets_qdisc_dequeue+0x1071/0x11b0 kernel/net/sched/sch_ets.c:481 Read of size 8 at addr ffff8880502fc018 by task ping/12308 > CPU: 0 UID: 0 PID: 12308 Comm: ping Not tainted 6.18.0-rc4-dirty #1 PREEMPT(full) Hardware name: QEMU Ubuntu 25.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack kernel/lib/dump_stack.c:94 dump_stack_lvl+0x100/0x190 kernel/lib/dump_stack.c:120 print_address_description kernel/mm/kasan/report.c:378 print_report+0x156/0x4c9 kernel/mm/kasan/report.c:482 kasan_report+0xdf/0x110 kernel/mm/kasan/report.c:595 ets_qdisc_dequeue+0x1071/0x11b0 kernel/net/sched/sch_ets.c:481 dequeue_skb kernel/net/sched/sch_generic.c:294 qdisc_restart kernel/net/sched/sch_generic.c:399 __qdisc_run+0x1c9/0x1b00 kernel/net/sched/sch_generic.c:417 __dev_xmit_skb kernel/net/core/dev.c:4221 __dev_queue_xmit+0x2848/0x4410 kernel/net/core/dev.c:4729 dev_queue_xmit kernel/./include/linux/netdevice.h:3365 [...] Allocated by task 17115: kasan_save_stack+0x30/0x50 kernel/mm/kasan/common.c:56 kasan_save_track+0x14/0x30 kernel/mm/kasan/common.c:77 poison_kmalloc_redzone kernel/mm/kasan/common.c:400 __kasan_kmalloc+0xaa/0xb0 kernel/mm/kasan/common.c:417 kasan_kmalloc kernel/./include/linux/kasan.h:262 __do_kmalloc_node kernel/mm/slub.c:5642 __kmalloc_node_noprof+0x34e/0x990 kernel/mm/slub.c:5648 kmalloc_node_noprof kernel/./include/linux/slab.h:987 qdisc_alloc+0xb8/0xc30 kernel/net/sched/sch_generic.c:950 qdisc_create_dflt+0x93/0x490 kernel/net/sched/sch_generic.c:1012 ets_class_graft+0x4fd/0x800 kernel/net/sched/sch_ets.c:261 qdisc_graft+0x3e4/0x1780 kernel/net/sched/sch_api.c:1196 [...] Freed by task 9905: kasan_save_stack+0x30/0x50 kernel/mm/kasan/common.c:56 kasan_save_track+0x14/0x30 kernel/mm/kasan/common.c:77 __kasan_save_free_info+0x3b/0x70 kernel/mm/kasan/generic.c:587 kasan_save_free_info kernel/mm/kasan/kasan.h:406 poison_slab_object kernel/mm/kasan/common.c:252 __kasan_slab_free+0x5f/0x80 kernel/mm/kasan/common.c:284 kasan_slab_free kernel/./include/linux/kasan.h:234 slab_free_hook kernel/mm/slub.c:2539 slab_free kernel/mm/slub.c:6630 kfree+0x144/0x700 kernel/mm/slub.c:6837 rcu_do_batch kernel/kernel/rcu/tree.c:2605 rcu_core+0x7c0/0x1500 kernel/kernel/rcu/tree.c:2861 handle_softirqs+0x1ea/0x8a0 kernel/kernel/softirq.c:622 __do_softirq kernel/kernel/softirq.c:656 [...] Commentary: 1. Maher Azzouzi working with Trend Micro Zero Day Initiative was reported as the person who found the issue. I requested to get a proper email to add to the reported-by tag but got no response. For this reason i will credit the person i exchanged emails with i.e zdi-disclosures@trendmicro.com 2. Neither i nor Victor who did a much more thorough testing was able to reproduce a UAF with the PoC or other approaches we tried. We were both able to reproduce a null ptr deref. After exchange with zdi-disclosures@trendmicro.com they sent a small change to be made to the code to add an extra delay which was able to simulate the UAF. i.e, this: qdisc_put(q->classes[i].qdisc); mdelay(90); q->classes[i].qdisc = NULL; I was informed by Thomas Gleixner(tglx@linutronix.de) that adding delays was acceptable approach for demonstrating the bug, quote: "Adding such delays is common exploit validation practice" The equivalent delay could happen "by virt scheduling the vCPU out, SMIs, NMIs, PREEMPT_RT enabled kernel" 3. I asked the OP to test and report back but got no response and after a few days gave up and proceeded to submit this fix. Fixes: de6d25924c2a ("net/sched: sch_ets: don't peek at classes beyond 'nbands'") 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/20251128151919.576920-1-jhs@mojatatu.com Signed-off-by: Paolo Abeni

net/sched: ets: use old 'nbands' while purging unused classes

2025-08-14T01:11:48+00:00

Shuang reported sch_ets test-case [1] crashing in ets_class_qlen_notify() after recent changes from Lion [2]. The problem is: in ets_qdisc_change() we purge unused DWRR queues; the value of 'q->nbands' is the new one, and the cleanup should be done with the old one. The problem is here since my first attempts to fix ets_qdisc_change(), but it surfaced again after the recent qdisc len accounting fixes. Fix it purging idle DWRR queues before assigning a new value of 'q->nbands', so that all purge operations find a consistent configuration: - old 'q->nbands' because it's needed by ets_class_find() - old 'q->nstrict' because it's needed by ets_class_is_strict() BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 62 UID: 0 PID: 39457 Comm: tc Kdump: loaded Not tainted 6.12.0-116.el10.x86_64 #1 PREEMPT(voluntary) Hardware name: Dell Inc. PowerEdge R640/06DKY5, BIOS 2.12.2 07/09/2021 RIP: 0010:__list_del_entry_valid_or_report+0x4/0x80 Code: ff 4c 39 c7 0f 84 39 19 8e ff b8 01 00 00 00 c3 cc cc cc cc 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <48> 8b 17 48 8b 4f 08 48 85 d2 0f 84 56 19 8e ff 48 85 c9 0f 84 ab RSP: 0018:ffffba186009f400 EFLAGS: 00010202 RAX: 00000000000000d6 RBX: 0000000000000000 RCX: 0000000000000004 RDX: ffff9f0fa29b69c0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffffffc12c2400 R08: 0000000000000008 R09: 0000000000000004 R10: ffffffffffffffff R11: 0000000000000004 R12: 0000000000000000 R13: ffff9f0f8cfe0000 R14: 0000000000100005 R15: 0000000000000000 FS: 00007f2154f37480(0000) GS:ffff9f269c1c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001530be001 CR4: 00000000007726f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ets_class_qlen_notify+0x65/0x90 [sch_ets] qdisc_tree_reduce_backlog+0x74/0x110 ets_qdisc_change+0x630/0xa40 [sch_ets] __tc_modify_qdisc.constprop.0+0x216/0x7f0 tc_modify_qdisc+0x7c/0x120 rtnetlink_rcv_msg+0x145/0x3f0 netlink_rcv_skb+0x53/0x100 netlink_unicast+0x245/0x390 netlink_sendmsg+0x21b/0x470 ____sys_sendmsg+0x39d/0x3d0 ___sys_sendmsg+0x9a/0xe0 __sys_sendmsg+0x7a/0xd0 do_syscall_64+0x7d/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f2155114084 Code: 89 02 b8 ff ff ff ff eb bb 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 80 3d 25 f0 0c 00 00 74 13 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 89 54 24 1c 48 89 RSP: 002b:00007fff1fd7a988 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000560ec063e5e0 RCX: 00007f2155114084 RDX: 0000000000000000 RSI: 00007fff1fd7a9f0 RDI: 0000000000000003 RBP: 00007fff1fd7aa60 R08: 0000000000000010 R09: 000000000000003f R10: 0000560ee9b3a010 R11: 0000000000000202 R12: 00007fff1fd7aae0 R13: 000000006891ccde R14: 0000560ec063e5e0 R15: 00007fff1fd7aad0 [1] https://lore.kernel.org/netdev/e08c7f4a6882f260011909a868311c6e9b54f3e4.1639153474.git.dcaratti@redhat.com/ [2] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/ Cc: stable@vger.kernel.org Fixes: 103406b38c60 ("net/sched: Always pass notifications when child class becomes empty") Fixes: c062f2a0b04d ("net/sched: sch_ets: don't remove idle classes from the round-robin list") Fixes: dcc68b4d8084 ("net: sch_ets: Add a new Qdisc") Reported-by: Li Shuang Closes: https://issues.redhat.com/browse/RHEL-108026 Reviewed-by: Petr Machata Co-developed-by: Ivan Vecera Signed-off-by: Ivan Vecera Signed-off-by: Davide Caratti Link: https://patch.msgid.link/7928ff6d17db47a2ae7cc205c44777b1f1950545.1755016081.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski

net_sched: ets: fix a race in ets_qdisc_change()

2025-06-12T15:05:50+00:00

Gerrard Tai reported a race condition in ETS, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock. Fixes: b05972f01e7d ("net: sched: tbf: don't call qdisc_put() while holding tree lock") Reported-by: Gerrard Tai Suggested-by: Gerrard Tai Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250611111515.1983366-5-edumazet@google.com Signed-off-by: Jakub Kicinski

net_sched: ets: Fix double list add in class with netem as child qdisc

2025-04-28T22:55:06+00:00

As described in Gerrard's report [1], there are use cases where a netem child qdisc will make the parent qdisc's enqueue callback reentrant. In the case of ets, there won't be a UAF, but the code will add the same classifier to the list twice, which will cause memory corruption. In addition to checking for qlen being zero, this patch checks whether the class was already added to the active_list (cl_is_active) before doing the addition to cater for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/ Fixes: 37d9cf1a3ce3 ("sched: Fix detection of empty queues in child qdiscs") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20250425220710.3964791-4-victor@mojatatu.com Signed-off-by: Jakub Kicinski