kernel/linux.git/net/sched, branch v6.18.35

net/sched: Revert "net/sched: Restrict conditions for adding duplicating netems to qdisc tree"

2026-06-09T10:28:30+00:00

[ Upstream commit eda0b7f203bb166c98d1418b204135bd566ac83b ] This reverts commit ec8e0e3d7adef940cdf9475e2352c0680189d14e. The original patch rejects any tree containing two netems when either has duplication set, even when they sit on unrelated classes of the same classful parent. That broke configurations that have worked since netem was introduced. The re-entrancy problem the original commit was trying to solve is handled by later patch using tc_depth flag. Doing this revert will (re)expose the original bug with multiple netem duplication. When this patch is backported make sure and get the full series. Fixes: ec8e0e3d7ade ("net/sched: Restrict conditions for adding duplicating netems to qdisc tree") Reported-by: Ji-Soo Chung Reported-by: Gerlinde Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220774 Reported-by: zyc zyc Closes: https://lore.kernel.org/all/19adda5a1e2.12410b78222774.9191120410578703463@zohomail.cn/ Reported-by: Manas Ghandat Closes: https://lore.kernel.org/netdev/f69b2c8f-8325-4c2e-a011-6dbc089f30e4@gmail.com/ Reviewed-by: Stephen Hemminger Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260525122556.973584-3-jhs@mojatatu.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

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

2026-06-09T10:28:23+00:00

[ Upstream commit 1b9bc71153b01dbde8045b9edede4240f4f5520e ] When sfb has children (eg qfq qdisc) whose peek() callback is qdisc_peek_dequeued(), we could get a kernel panic. When the parent of such qdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from its child (sfb in this case), it will do the following: 1a. do a peek() - and when sensing there's an skb the child can offer, then - the child in this case(sfb) calls its child's (qfq) peek. qfq does the right thing and will return the gso_skb queue packet. Note: if there wasnt a gso_skb entry then qfq will store it there. 1b. invoke a dequeue() on the child (sfb). And herein lies the problem. - sfb will call the child's dequeue() which will essentially just try to grab something of qfq's queue. [ 127.594489][ T453] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 127.594741][ T453] CPU: 2 UID: 0 PID: 453 Comm: ping Not tainted 7.1.0-rc1-00035-gac961974495b-dirty #793 PREEMPT(full) [ 127.595059][ T453] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 127.595254][ T453] RIP: 0010:qfq_dequeue+0x35c/0x1650 [sch_qfq] [ 127.595461][ T453] Code: 00 fc ff df 80 3c 02 00 0f 85 17 0e 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 76 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b [ 127.596081][ T453] RSP: 0018:ffff88810e5af440 EFLAGS: 00010216 [ 127.596337][ T453] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 127.596623][ T453] RDX: 0000000000000009 RSI: 0000001880000000 RDI: ffff888104fd82b0 [ 127.596917][ T453] RBP: ffff888104fd8000 R08: ffff888104fd8280 R09: 1ffff110211893a3 [ 127.597165][ T453] R10: 1ffff110211893a6 R11: 1ffff110211893a7 R12: 0000001880000000 [ 127.597404][ T453] R13: ffff888104fd82b8 R14: 0000000000000048 R15: 0000000040000000 [ 127.597644][ T453] FS: 00007fc380cbfc40(0000) GS:ffff88816f2a8000(0000) knlGS:0000000000000000 [ 127.597956][ T453] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 127.598160][ T453] CR2: 00005610aa9890a8 CR3: 000000010369e000 CR4: 0000000000750ef0 [ 127.598390][ T453] PKRU: 55555554 [ 127.598509][ T453] Call Trace: [ 127.598629][ T453] [ 127.598718][ T453] ? mark_held_locks+0x40/0x70 [ 127.598890][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599053][ T453] sfb_dequeue+0x88/0x4d0 [ 127.599174][ T453] ? ktime_get+0x137/0x230 [ 127.599328][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599480][ T453] ? qdisc_peek_dequeued+0x7b/0x350 [sch_qfq] [ 127.599670][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599831][ T453] tbf_dequeue+0x6b1/0x1098 [sch_tbf] [ 127.599988][ T453] __qdisc_run+0x169/0x1900 The right thing to do in #1b is to grab the skb off gso_skb queue. This patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked() method instead. Fixes: e13e02a3c68d ("net_sched: SFB flow scheduler") Signed-off-by: Victor Nogueria Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260430152957.194015-3-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: cls_fw: fix NULL dereference of "old" filters before change()

2026-06-09T10:28:23+00:00

[ Upstream commit 65782b2db7321d5f97c16718c4c7f6c7205a56be ] Like pointed out by Sashiko [1], since commit ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") TC filters are added to a shared block and published to datapath before their ->change() function is called. This is a problem for cls_fw: an invalid filter created with the "old" method can still classify some packets before it is destroyed by the validation logic added by Xiang. Therefore, insisting with repeated runs of the following script: # ip link add dev crash0 type dummy # ip link set dev crash0 up # mausezahn crash0 -c 100000 -P 10 \ > -A 4.3.2.1 -B 1.2.3.4 -t udp "dp=1234" -q & # sleep 1 # tc qdisc add dev crash0 egress_block 1 clsact # tc filter add block 1 protocol ip prio 1 matchall \ > action skbedit mark 65536 continue # tc filter add block 1 protocol ip prio 2 fw # ip link del dev crash0 can still make fw_classify() hit the WARN_ON() in [2]: WARNING: ./include/net/pkt_cls.h:88 at fw_classify+0x244/0x250 [cls_fw], CPU#18: mausezahn/1399 Modules linked in: cls_fw(E) act_skbedit(E) CPU: 18 UID: 0 PID: 1399 Comm: mausezahn Tainted: G E 7.0.0-rc6-virtme #17 PREEMPT(full) Tainted: [E]=UNSIGNED_MODULE Hardware name: Red Hat KVM, BIOS 1.16.3-2.el9 04/01/2014 RIP: 0010:fw_classify+0x244/0x250 [cls_fw] Code: 5c 49 c7 45 00 00 00 00 00 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 5b b8 ff ff ff ff 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 90 <0f> 0b 90 eb a0 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffd1b7026bf8a8 EFLAGS: 00010202 RAX: ffff8c5ac9c60800 RBX: ffff8c5ac99322c0 RCX: 0000000000000004 RDX: 0000000000000001 RSI: ffff8c5b74d7a000 RDI: ffff8c5ac8284f40 RBP: ffffd1b7026bf8d0 R08: 0000000000000000 R09: ffffd1b7026bf9b0 R10: 00000000ffffffff R11: 0000000000000000 R12: 0000000000010000 R13: ffffd1b7026bf930 R14: ffff8c5ac8284f40 R15: 0000000000000000 FS: 00007fca40c37740(0000) GS:ffff8c5b74d7a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fca40e822a0 CR3: 0000000005ca0001 CR4: 0000000000172ef0 Call Trace: tcf_classify+0x17d/0x5c0 tc_run+0x9d/0x150 __dev_queue_xmit+0x2ab/0x14d0 ip_finish_output2+0x340/0x8f0 ip_output+0xa4/0x250 raw_sendmsg+0x147d/0x14b0 __sys_sendto+0x1cc/0x1f0 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x126/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fca40e822ba Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89 RSP: 002b:00007ffc248a42c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 000055ef233289d0 RCX: 00007fca40e822ba RDX: 000000000000001e RSI: 000055ef23328c30 RDI: 0000000000000003 RBP: 000055ef233289d0 R08: 00007ffc248a42d0 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001e R13: 00000000000186a0 R14: 0000000000000000 R15: 00007fca41043000 irq event stamp: 1045778 hardirqs last enabled at (1045784): [] __up_console_sem+0x52/0x60 hardirqs last disabled at (1045789): [] __up_console_sem+0x37/0x60 softirqs last enabled at (1045426): [] __alloc_skb+0x207/0x260 softirqs last disabled at (1045434): [] __dev_queue_xmit+0x78/0x14d0 Then, because of the value in the packet's mark, dereference on 'q->handle' with NULL 'q' occurs: BUG: kernel NULL pointer dereference, address: 0000000000000038 [...] RIP: 0010:fw_classify+0x1fe/0x250 [cls_fw] [...] Skip "old-style" classification on shared blocks, so that the NULL dereference is fixed and WARN_ON() is not hit anymore in the short lifetime of invalid cls_fw "old-style" filters. [1] https://sashiko.dev/#/patchset/20260331050217.504278-1-xmei5%40asu.edu [2] https://elixir.bootlin.com/linux/v7.0-rc6/source/include/net/pkt_cls.h#L86 Fixes: faeea8bbf6e9 ("net/sched: cls_fw: fix NULL pointer dereference on shared blocks") Fixes: ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") Acked-by: Jamal Hadi Salim Signed-off-by: Davide Caratti Link: https://patch.msgid.link/e39cbd3103a337f1e515d186fe697b4459d24757.1775661704.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: sch_pie: annotate more data-races in pie_dump_stats()

2026-05-23T11:07:14+00:00

[ Upstream commit 6d4106e8df94c0c52cf3ca6a6a0d01567fb3844e ] My prior patch missed few READ_ONCE()/WRITE_ONCE() annotations. Fixes: 5154561d9b11 ("net/sched: sch_pie: annotate data-races in pie_dump_stats()") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260430080056.35104-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: cls_flower: revert unintended changes

2026-05-23T11:07:14+00:00

[ Upstream commit 1e01abec856593e02cd69fd95b784c10dd46880c ] While applying the blamed commit 4ca07b9239bd ("net: mctp i2c: check length before marking flow active"), I unintentionally included unrelated and unacceptable changes. Revert them. Fixes: 4ca07b9239bd ("net: mctp i2c: check length before marking flow active") Reported-by: Jeremy Kerr Closes: https://lore.kernel.org/netdev/bd8704fe0bd53e278add5cde4873256656623e2e.camel@codeconstruct.com.au/ Signed-off-by: Paolo Abeni Link: https://patch.msgid.link/043026a53ff84da88b17648c4b0d17f0331749cb.1777447863.git.pabeni@redhat.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: sch_cake: annotate data-races in cake_dump_stats() (V)

2026-05-23T11:07:12+00:00

[ Upstream commit a6c95b833dc17e84d16a8ac0f40fd0931616a52d ] cake_dump_stats() runs without qdisc spinlock being held. In this final patch, I add READ_ONCE()/WRITE_ONCE() annotations for cparams.target and cparams.interval. Fixes: 046f6fd5daef ("sched: Add Common Applications Kept Enhanced (cake) qdisc") Signed-off-by: Eric Dumazet Acked-by: "Toke Høiland-Jørgensen" Link: https://patch.msgid.link/20260427083606.459355-6-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: sch_cake: annotate data-races in cake_dump_stats() (III)

2026-05-23T11:07:11+00:00

[ Upstream commit 276a98a434964088fccd4745db5b34d6e831e358 ] cake_dump_stats() runs without qdisc spinlock being held. In this third patch, I add READ_ONCE()/WRITE_ONCE() annotations for the following fields: - packets - tin_dropped - tin_ecn_mark - ack_drops - peak_delay - avge_delay - base_delay Other annotations are added in following patches, to ease code review. Fixes: 046f6fd5daef ("sched: Add Common Applications Kept Enhanced (cake) qdisc") Signed-off-by: Eric Dumazet Acked-by: "Toke Høiland-Jørgensen" Link: https://patch.msgid.link/20260427083606.459355-4-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: mctp i2c: check length before marking flow active

2026-05-23T11:07:10+00:00

[ Upstream commit 4ca07b9239bd0478ae586632a2ed72be37ed8407 ] Currently, mctp_i2c_get_tx_flow_state() is called before the packet length sanity check. This function marks a new flow as active in the MCTP core. If the sanity check fails, mctp_i2c_xmit() returns early without calling mctp_i2c_lock_nest(). This results in a mismatched locking state: the flow is active, but the I2C bus lock was never acquired for it. When the flow is later released, mctp_i2c_release_flow() will see the active state and queue an unlock marker. The TX thread will then decrement midev->i2c_lock_count from 0, causing it to underflow to -1. This underflow permanently breaks the driver's locking logic, allowing future transmissions to occur without holding the I2C bus lock, leading to bus collisions and potential hardware hangs. Move the mctp_i2c_get_tx_flow_state() call to after the length sanity check to ensure we only transition the flow state if we are actually going to proceed with the transmission and locking. Fixes: f5b8abf9fc3d ("mctp i2c: MCTP I2C binding driver") Signed-off-by: William A. Kennington III Acked-by: Jeremy Kerr Link: https://patch.msgid.link/20260423074741.201460-1-william@wkennington.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net/sched: taprio: fix NULL pointer dereference in class dump

2026-05-23T11:07:09+00:00

[ Upstream commit 3d07ca5c0fae311226f737963984bd94bb159a87 ] When a TAPRIO child qdisc is deleted via RTM_DELQDISC, taprio_graft() is called with new == NULL and stores NULL into q->qdiscs[cl - 1]. Subsequent RTM_GETTCLASS dump operations walk all classes via taprio_walk() and call taprio_dump_class(), which calls taprio_leaf() returning the NULL pointer, then dereferences it to read child->handle, causing a kernel NULL pointer dereference. The bug is reachable with namespace-scoped CAP_NET_ADMIN on any kernel with CONFIG_NET_SCH_TAPRIO enabled. On systems with unprivileged user namespaces enabled, an unprivileged local user can trigger a kernel panic by creating a taprio qdisc inside a new network namespace, grafting an explicit child qdisc, deleting it, and requesting a class dump. The RTM_GETTCLASS dump itself requires no capability. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:taprio_dump_class (net/sched/sch_taprio.c:2478) Call Trace: tc_fill_tclass (net/sched/sch_api.c:1966) qdisc_class_dump (net/sched/sch_api.c:2326) taprio_walk (net/sched/sch_taprio.c:2514) tc_dump_tclass_qdisc (net/sched/sch_api.c:2352) tc_dump_tclass_root (net/sched/sch_api.c:2370) tc_dump_tclass (net/sched/sch_api.c:2431) rtnl_dumpit (net/core/rtnetlink.c:6864) netlink_dump (net/netlink/af_netlink.c:2325) rtnetlink_rcv_msg (net/core/rtnetlink.c:6959) netlink_rcv_skb (net/netlink/af_netlink.c:2550) Fix this by substituting &noop_qdisc when new is NULL in taprio_graft(), a common pattern used by other qdiscs (e.g., multiq_graft()) to ensure the q->qdiscs[] slots are never NULL. This makes control-plane dump paths safe without requiring individual NULL checks. Since the data-plane paths (taprio_enqueue and taprio_dequeue_from_txq) previously had explicit NULL guards that would drop/skip the packet cleanly, update those checks to test for &noop_qdisc instead. Without this, packets would reach taprio_enqueue_one() which increments the root qdisc's qlen and backlog before calling the child's enqueue; noop_qdisc drops the packet but those counters are never rolled back, permanently inflating the root qdisc's statistics. After this change *old can be a valid qdisc, NULL, or &noop_qdisc. Only call qdisc_put(*old) in the first case to avoid decreasing noop_qdisc's refcount, which was never increased. Fixes: 665338b2a7a0 ("net/sched: taprio: dump class stats for the actual q->qdiscs[]") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Acked-by: Jamal Hadi Salim Tested-by: Weiming Shi Link: https://patch.msgid.link/20260422161958.2517539-3-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: sch_fq_pie: annotate data-races in fq_pie_dump_stats()

2026-05-23T11:07:09+00:00

[ Upstream commit 59b145771c7982cfe9020d4e9e22da92d6b5ae31 ] fq_codel_dump_stats() acquires the qdisc spinlock a bit too late. Move this acquisition before we fill tc_fq_pie_xstats with live data. Alternative would be to add READ_ONCE() and WRITE_ONCE() annotations, but the spinlock is needed anyway to scan q->new_flows and q->old_flows. Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler") Signed-off-by: Eric Dumazet Reviewed-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260423063527.2568262-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin