kernel/linux.git/net/sched, branch v7.2-rc1

net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle

2026-06-24T02:08:36+00:00

tcf_classify() can return TC_ACT_CONSUMED while the skb is held by the defragmentation engine (e.g. act_ct on out-of-order fragments). When that happens the skb is no longer owned by the caller and must not be touched again. tcf_qevent_handle() did not handle TC_ACT_CONSUMED: it fell through the switch and returned the skb to the caller as if classification had passed. The only qdisc that wires up qevents today is RED, via three call sites (qe_mark on RED_PROB_MARK/HARD_MARK, qe_early_drop on congestion_drop) red_enqueue() was continuing to operate on an skb it no longer owns in this case -- enqueueing it, dropping it, or updating statistics. Resulting in a UAF. tc qdisc add dev eth0 root handle 1: red ... qevent early_drop block 10 tc filter add block 10 ... action ct (with ct defrag enabled and traffic that produces out-of-order fragments, e.g. a fragmented UDP stream) Handle TC_ACT_CONSUMED in tcf_qevent_handle() the same way the ingress and egress fast paths do: treat it as stolen and return NULL without touching the skb. Unlike the TC_ACT_STOLEN case, the skb must not be dropped/freed here, as it is no longer owned by us. Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") Reported-by: Zero Day Initiative Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260620130749.226642-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski

net: do not acquire dev->tx_global_lock in netdev_watchdog_up()

2026-06-23T21:40:33+00:00

Marek Szyprowski reported a deadlock during system resume when virtio_net driver is used. The deadlock occurs because netif_device_attach() is called while holding dev->tx_global_lock (via netif_tx_lock_bh() in virtnet_restore_up()). netif_device_attach() calls __netdev_watchdog_up(), which now also tries to acquire dev->tx_global_lock to synchronize with dev_watchdog(). This recursive lock acquisition results in a deadlock. Fix this by removing the tx_global_lock acquisition from netdev_watchdog_up(). The critical state (watchdog_timer and watchdog_ref_held) is already protected by dev->watchdog_lock, which was introduced in the blamed commit. Fixes: 8eed5519e496 ("net: watchdog: fix refcount tracking races") Reported-by: Marek Szyprowski Closes: https://lore.kernel.org/netdev/a443376e-5187-4268-93b3-58047ef113a8@samsung.com/ Signed-off-by: Eric Dumazet Tested-by: Marek Szyprowski Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260622110108.69541-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: dualpi2: fix GSO backlog accounting

2026-06-21T22:16:03+00:00

When DualPI2 splits a GSO skb into N segments, it propagates N additional packets to its parent before returning NET_XMIT_SUCCESS. The parent then accounts for the original skb once more, leaving its qlen one larger than the number of packets actually queued. With QFQ as the parent, after all real packets are dequeued, QFQ still has a non-zero qlen while its in-service aggregate has no active classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes the result to qfq_peek_skb(), causing a NULL pointer dereference. Follow the same pattern used by tbf_segment() and taprio: count only successfully queued segments, propagate the difference between the original skb and those segments, and return NET_XMIT_SUCCESS whenever at least one segment was queued. Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc") Cc: stable@vger.kernel.org Signed-off-by: Xingquan Liu Acked-by: Jamal Hadi Salim Reviewed-by: Victor Nogueira Link: https://patch.msgid.link/20260619151447.223640-1-b1n@b1n.io Signed-off-by: Jakub Kicinski

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

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

2026-06-16T21:59:58+00:00

Merge in late fixes in preparation for the net-next PR. Conflicts: net/tls/tls_sw.c 406e8a651a7b ("net: skmsg: preserve sg.copy across SG transforms") 79511603a65b ("tls: remove dead sockmap (psock) handling from the SW path") drivers/net/ethernet/microsoft/mana/mana_en.c f8fd56977eeea ("net: mana: guard TX wq object destroy with INVALID_MANA_HANDLE check") d07efe5a6e641 ("net: mana: Use per-queue allocation for tx_qp to reduce allocation size") https://lore.kernel.org/ajAPXu-C_PuTgV-a@sirena.org.uk No adjacent changes. Signed-off-by: Jakub Kicinski

net/sched: act_csum: don't mangle UDP tunnel GSO packets

2026-06-14T11:27:39+00:00

Similar to commit add641e7dee3 ("sched: act_csum: don't mangle TCP and UDP GSO packets"), UDP tunnel GSO packets going through act_csum shouldn't have their checksum calculated at this point, because it will be done after segmentation. Setting the checksum in act_csum modifies skb->ip_summed and prevents inner IP csum offload from kicking in, resulting in a packet with a bad checksum. Add UDP tunnel GSO packets to the exceptions, and also add UDP GSO (SKB_GSO_UDP_L4), as the same logic as in the commit mentioned above applies to UDP GSO too. Signed-off-by: Alice Mikityanska Reviewed-by: Davide Caratti Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260611192955.604661-2-alice.kernel@fastmail.im Signed-off-by: Paolo Abeni

net/sched: sch_dualpi2: Add missing module alias

2026-06-13T00:59:32+00:00

When a qdisc is added by name, the kernel tries to autoload its module via request_qdisc_module(), which calls: request_module(NET_SCH_ALIAS_PREFIX "%s", name); i.e. it asks modprobe to resolve the "net-sch-" alias (e.g. "net-sch-dualpi2") rather than the module's file name. Since dualpi2 was shipped without this alias, the autoload fails: tc qdisc add dev lo root handle 1: dualpi2 Error: Specified qdisc kind is unknown. Fix this by adding the missing alias so the qdisc is autoloaded on demand like the others. Fixes: 320d031ad6e4 ("sched: Struct definition and parsing of dualpi2 qdisc") Signed-off-by: Victor Nogueira Reviewed-by: Pedro Tammela Link: https://patch.msgid.link/20260611205849.3287640-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net: watchdog: fix refcount tracking races

2026-06-13T00:34:57+00:00

Blamed commit converted the untracked dev_hold()/dev_put() calls in the watchdog code to use the tracked dev_hold_track()/dev_put_track() (which were later renamed/interfaced to netdev_hold() and netdev_put()). By introducing dev->watchdog_dev_tracker to store the reference tracking information without adding synchronization between netdev_watchdog_up() and dev_watchdog(), it enabled the race condition where this pointer could be overwritten or freed concurrently, leading to the list corruption crash syzbot reported: list_del corruption, ffff888114a18c00->next is NULL kernel BUG at lib/list_debug.c:52 ! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 91 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound linkwatch_event RIP: 0010:__list_del_entry_valid_or_report.cold+0x22/0x2a lib/list_debug.c:52 Call Trace: __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_move_tail include/linux/list.h:341 [inline] ref_tracker_free+0x1a7/0x6c0 lib/ref_tracker.c:329 netdev_tracker_free include/linux/netdevice.h:4491 [inline] netdev_put include/linux/netdevice.h:4508 [inline] netdev_put include/linux/netdevice.h:4504 [inline] netdev_watchdog_down net/sched/sch_generic.c:600 [inline] dev_deactivate_many+0x28c/0xfe0 net/sched/sch_generic.c:1363 dev_deactivate+0x109/0x1d0 net/sched/sch_generic.c:1397 linkwatch_do_dev net/core/link_watch.c:184 [inline] linkwatch_do_dev+0xd3/0x120 net/core/link_watch.c:166 __linkwatch_run_queue+0x3a5/0x810 net/core/link_watch.c:240 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:314 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 This patch has three coordinated parts: 1) Add dev->watchdog_lock and dev->watchdog_ref_held to serialize watchdog operations. 2) Remove netdev_watchdog_up() call from netif_carrier_on(): This ensures netdev_watchdog_up() is only called from process/BH context (via linkwatch workqueue dev_activate()), allowing us to use spin_lock_bh() for synchronization. 3) Synchronize watchdog up and watchdog timer: Protect netdev_watchdog_up() with tx_global_lock and watchdog_lock. Only allocate a new tracker in netdev_watchdog_up() if one is not already present. In dev_watchdog(), ensure we don't release the tracker if the timer was rescheduled either by dev_watchdog() itself or concurrently by netdev_watchdog_up(). Fixes: f12bf6f3f942 ("net: watchdog: add net device refcount tracker") Reported-by: syzbot+381d82bbf0253710b35d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a26b751.c25708ab.1b19ef.0013.GAE@google.com/T/#u Tested-by: syzbot+3479efbc2821cb2a79f2@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260611152737.2580480-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen

2026-06-13T00:20:53+00:00

Whenever dualpi2 drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though dualpi2 still has 1 packet on the queue and, thus, mistakenly deactivates the parent's class which leads to a null-ptr-deref: [ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI [ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full) [ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq [ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b All code [ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216 [ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0 [ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523 [ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000 [ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000 [ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000 [ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0 [ 101.431320][ T599] PKRU: 55555554 [ 101.431433][ T599] Call Trace: [ 101.431544][ T599] [ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445) [ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22)) [ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored. Fixes: 8f9516daedd6 ("sched: Add enqueue/dequeue of dualpi2 qdisc") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20260610192855.3121513-4-victor@mojatatu.com Signed-off-by: Jakub Kicinski