kernel/net/sched/sch_teql.c, branch linux-rolling-stable

net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit

2026-03-19T15:14:51Z

[ Upstream commit 0cc0c2e661af418bbf7074179ea5cfffc0a5c466 ] teql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit through slave devices, but does not update skb->dev to the slave device beforehand. When a gretap tunnel is a TEQL slave, the transmit path reaches iptunnel_xmit() which saves dev = skb->dev (still pointing to teql0 master) and later calls iptunnel_xmit_stats(dev, pkt_len). This function does: get_cpu_ptr(dev->tstats) Since teql_master_setup() does not set dev->pcpu_stat_type to NETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats for teql0, so dev->tstats is NULL. get_cpu_ptr(NULL) computes NULL + __per_cpu_offset[cpu], resulting in a page fault. BUG: unable to handle page fault for address: ffff8880e6659018 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 68bc067 P4D 68bc067 PUD 0 Oops: Oops: 0002 [#1] SMP KASAN PTI RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89) Call Trace: ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847) __gre_xmit (net/ipv4/ip_gre.c:478) gre_tap_xmit (net/ipv4/ip_gre.c:779) teql_master_xmit (net/sched/sch_teql.c:319) dev_hard_start_xmit (net/core/dev.c:3887) sch_direct_xmit (net/sched/sch_generic.c:347) __dev_queue_xmit (net/core/dev.c:4802) neigh_direct_output (net/core/neighbour.c:1660) ip_finish_output2 (net/ipv4/ip_output.c:237) __ip_finish_output.part.0 (net/ipv4/ip_output.c:315) ip_mc_output (net/ipv4/ip_output.c:369) ip_send_skb (net/ipv4/ip_output.c:1508) udp_send_skb (net/ipv4/udp.c:1195) udp_sendmsg (net/ipv4/udp.c:1485) inet_sendmsg (net/ipv4/af_inet.c:859) __sys_sendto (net/socket.c:2206) Fix this by setting skb->dev = slave before calling netdev_start_xmit(), so that tunnel xmit functions see the correct slave device with properly allocated tstats. Fixes: 039f50629b7f ("ip_tunnel: Move stats update to iptunnel_xmit()") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Link: https://patch.msgid.link/20260304044216.3517851-3-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/sched: Enforce that teql can only be used as root qdisc

2026-01-19T20:06:41Z

Design intent of teql is that it is only supposed to be used as root qdisc. We need to check for that constraint. Although not important, I will describe the scenario that unearthed this issue for the curious. GangMin Kim managed to concot a scenario as follows: ROOT qdisc 1:0 (QFQ) ├── class 1:1 (weight=15, lmax=16384) netem with delay 6.4s └── class 1:2 (weight=1, lmax=1514) teql GangMin sends a packet which is enqueued to 1:1 (netem). Any invocation of dequeue by QFQ from this class will not return a packet until after 6.4s. In the meantime, a second packet is sent and it lands on 1:2. teql's enqueue will return success and this will activate class 1:2. Main issue is that teql only updates the parent visible qlen (sch->q.qlen) at dequeue. Since QFQ will only call dequeue if peek succeeds (and teql's peek always returns NULL), dequeue will never be called and thus the qlen will remain as 0. With that in mind, when GangMin updates 1:2's lmax value, the qfq_change_class calls qfq_deact_rm_from_agg. Since the child qdisc's qlen was not incremented, qfq fails to deactivate the class, but still frees its pointers from the aggregate. So when the first packet is rescheduled after 6.4 seconds (netem's delay), a dangling pointer is accessed causing GangMin's causing a UAF. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: GangMin Kim Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260114160243.913069-2-jhs@mojatatu.com Signed-off-by: Jakub Kicinski

net: annotate writes on dev->mtu from ndo_change_mtu()

2024-05-07T23:19:14Z

Simon reported that ndo_change_mtu() methods were never updated to use WRITE_ONCE(dev->mtu, new_mtu) as hinted in commit 501a90c94510 ("inet: protect against too small mtu values.") We read dev->mtu without holding RTNL in many places, with READ_ONCE() annotations. It is time to take care of ndo_change_mtu() methods to use corresponding WRITE_ONCE() Signed-off-by: Eric Dumazet Reported-by: Simon Horman Closes: https://lore.kernel.org/netdev/20240505144608.GB67882@kernel.org/ Reviewed-by: Jacob Keller Reviewed-by: Sabrina Dubroca Reviewed-by: Simon Horman Acked-by: Shannon Nelson Link: https://lore.kernel.org/r/20240506102812.3025432-1-edumazet@google.com Signed-off-by: Jakub Kicinski

rtnetlink: do not depend on RTNL for IFLA_TXQLEN output

2024-05-07T09:14:50Z

rtnl_fill_ifinfo() can read dev->tx_queue_len locklessly, granted we add corresponding READ_ONCE()/WRITE_ONCE() annotations. Add missing READ_ONCE(dev->tx_queue_len) in teql_enqueue() Signed-off-by: Eric Dumazet Signed-off-by: Paolo Abeni

net: sched: Fill in missing MODULE_DESCRIPTION for qdiscs

2023-11-02T04:49:09Z

W=1 builds now warn if module is built without a MODULE_DESCRIPTION(). Fill in missing MODULE_DESCRIPTIONs for TC qdiscs. Signed-off-by: Victor Nogueira Acked-by: Jamal Hadi Salim Reviewed-by: Vinicius Costa Gomes Link: https://lore.kernel.org/r/20231027155045.46291-4-victor@mojatatu.com Signed-off-by: Jakub Kicinski

net: sched: add rcu annotations around qdisc->qdisc_sleeping

2023-06-07T09:25:39Z

syzbot reported a race around qdisc->qdisc_sleeping [1] It is time we add proper annotations to reads and writes to/from qdisc->qdisc_sleeping. [1] BUG: KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu read to 0xffff8881286fc618 of 8 bytes by task 6928 on cpu 1: qdisc_lookup_rcu+0x192/0x2c0 net/sched/sch_api.c:331 __tcf_qdisc_find+0x74/0x3c0 net/sched/cls_api.c:1174 tc_get_tfilter+0x18f/0x990 net/sched/cls_api.c:2547 rtnetlink_rcv_msg+0x7af/0x8c0 net/core/rtnetlink.c:6386 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd write to 0xffff8881286fc618 of 8 bytes by task 6912 on cpu 0: dev_graft_qdisc+0x4f/0x80 net/sched/sch_generic.c:1115 qdisc_graft+0x7d0/0xb60 net/sched/sch_api.c:1103 tc_modify_qdisc+0x712/0xf10 net/sched/sch_api.c:1693 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503 ___sys_sendmsg net/socket.c:2557 [inline] __sys_sendmsg+0x1e3/0x270 net/socket.c:2586 __do_sys_sendmsg net/socket.c:2595 [inline] __se_sys_sendmsg net/socket.c:2593 [inline] __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 6912 Comm: syz-executor.5 Not tainted 6.4.0-rc3-syzkaller-00190-g0d85b27b0cc6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023 Fixes: 3a7d0d07a386 ("net: sched: extend Qdisc with rcu") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Vlad Buslov Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller

net: sched: delete duplicate cleanup of backlog and qlen

2022-08-25T13:10:17Z

qdisc_reset() is clearing qdisc->q.qlen and qdisc->qstats.backlog _after_ calling qdisc->ops->reset. There is no need to clear them again in the specific reset function. Signed-off-by: Zhengchao Shao Link: https://lore.kernel.org/r/20220824005231.345727-1-shaozhengchao@huawei.com Signed-off-by: Paolo Abeni

net_sched: move from strlcpy with unused retval to strscpy

2022-08-23T01:07:26Z

Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Signed-off-by: Wolfram Sang Link: https://lore.kernel.org/r/20220818210228.8635-1-wsa+renesas@sang-engineering.com Signed-off-by: Jakub Kicinski

net: sched: sch_teql: fix null-pointer dereference

2021-04-08T21:14:42Z

Reproduce: modprobe sch_teql tc qdisc add dev teql0 root teql0 This leads to (for instance in Centos 7 VM) OOPS: [ 532.366633] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8 [ 532.366733] IP: [] teql_destroy+0x18/0x100 [sch_teql] [ 532.366825] PGD 80000001376d5067 PUD 137e37067 PMD 0 [ 532.366906] Oops: 0000 [#1] SMP [ 532.366987] Modules linked in: sch_teql ... [ 532.367945] CPU: 1 PID: 3026 Comm: tc Kdump: loaded Tainted: G ------------ T 3.10.0-1062.7.1.el7.x86_64 #1 [ 532.368041] Hardware name: Virtuozzo KVM, BIOS 1.11.0-2.vz7.2 04/01/2014 [ 532.368125] task: ffff8b7d37d31070 ti: ffff8b7c9fdbc000 task.ti: ffff8b7c9fdbc000 [ 532.368224] RIP: 0010:[] [] teql_destroy+0x18/0x100 [sch_teql] [ 532.368320] RSP: 0018:ffff8b7c9fdbf8e0 EFLAGS: 00010286 [ 532.368394] RAX: ffffffffc0612490 RBX: ffff8b7cb1565e00 RCX: ffff8b7d35ba2000 [ 532.368476] RDX: ffff8b7d35ba2000 RSI: 0000000000000000 RDI: ffff8b7cb1565e00 [ 532.368557] RBP: ffff8b7c9fdbf8f8 R08: ffff8b7d3fd1f140 R09: ffff8b7d3b001600 [ 532.368638] R10: ffff8b7d3b001600 R11: ffffffff84c7d65b R12: 00000000ffffffd8 [ 532.368719] R13: 0000000000008000 R14: ffff8b7d35ba2000 R15: ffff8b7c9fdbf9a8 [ 532.368800] FS: 00007f6a4e872740(0000) GS:ffff8b7d3fd00000(0000) knlGS:0000000000000000 [ 532.368885] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 532.368961] CR2: 00000000000000a8 CR3: 00000001396ee000 CR4: 00000000000206e0 [ 532.369046] Call Trace: [ 532.369159] [] qdisc_create+0x36e/0x450 [ 532.369268] [] ? ns_capable+0x29/0x50 [ 532.369366] [] ? nla_parse+0x32/0x120 [ 532.369442] [] tc_modify_qdisc+0x13c/0x610 [ 532.371508] [] rtnetlink_rcv_msg+0xa7/0x260 [ 532.372668] [] ? sock_has_perm+0x75/0x90 [ 532.373790] [] ? rtnl_newlink+0x890/0x890 [ 532.374914] [] netlink_rcv_skb+0xab/0xc0 [ 532.376055] [] rtnetlink_rcv+0x28/0x30 [ 532.377204] [] netlink_unicast+0x170/0x210 [ 532.378333] [] netlink_sendmsg+0x308/0x420 [ 532.379465] [] sock_sendmsg+0xb6/0xf0 [ 532.380710] [] ? __xfs_filemap_fault+0x8e/0x1d0 [xfs] [ 532.381868] [] ? xfs_filemap_fault+0x2c/0x30 [xfs] [ 532.383037] [] ? __do_fault.isra.61+0x8a/0x100 [ 532.384144] [] ___sys_sendmsg+0x3e9/0x400 [ 532.385268] [] ? handle_mm_fault+0x39d/0x9b0 [ 532.386387] [] ? __do_page_fault+0x238/0x500 [ 532.387472] [] __sys_sendmsg+0x51/0x90 [ 532.388560] [] SyS_sendmsg+0x12/0x20 [ 532.389636] [] system_call_fastpath+0x25/0x2a [ 532.390704] [] ? system_call_after_swapgs+0xae/0x146 [ 532.391753] Code: 00 00 00 00 00 00 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 e5 41 55 41 54 53 48 8b b7 48 01 00 00 48 89 fb <48> 8b 8e a8 00 00 00 48 85 c9 74 43 48 89 ca eb 0f 0f 1f 80 00 [ 532.394036] RIP [] teql_destroy+0x18/0x100 [sch_teql] [ 532.395127] RSP [ 532.396179] CR2: 00000000000000a8 Null pointer dereference happens on master->slaves dereference in teql_destroy() as master is null-pointer. When qdisc_create() calls teql_qdisc_init() it imediately fails after check "if (m->dev == dev)" because both devices are teql0, and it does not set qdisc_priv(sch)->m leaving it zero on error path, then qdisc_create() imediately calls teql_destroy() which does not expect zero master pointer and we get OOPS. Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation") Signed-off-by: Pavel Tikhomirov Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

sched: consistently handle layer3 header accesses in the presence of VLANs

2020-07-03T21:34:53Z

There are a couple of places in net/sched/ that check skb->protocol and act on the value there. However, in the presence of VLAN tags, the value stored in skb->protocol can be inconsistent based on whether VLAN acceleration is enabled. The commit quoted in the Fixes tag below fixed the users of skb->protocol to use a helper that will always see the VLAN ethertype. However, most of the callers don't actually handle the VLAN ethertype, but expect to find the IP header type in the protocol field. This means that things like changing the ECN field, or parsing diffserv values, stops working if there's a VLAN tag, or if there are multiple nested VLAN tags (QinQ). To fix this, change the helper to take an argument that indicates whether the caller wants to skip the VLAN tags or not. When skipping VLAN tags, we make sure to skip all of them, so behaviour is consistent even in QinQ mode. To make the helper usable from the ECN code, move it to if_vlan.h instead of pkt_sched.h. v3: - Remove empty lines - Move vlan variable definitions inside loop in skb_protocol() - Also use skb_protocol() helper in IP{,6}_ECN_decapsulate() and bpf_skb_ecn_set_ce() v2: - Use eth_type_vlan() helper in skb_protocol() - Also fix code that reads skb->protocol directly - Change a couple of 'if/else if' statements to switch constructs to avoid calling the helper twice Reported-by: Ilya Ponetayev Fixes: d8b9605d2697 ("net: sched: fix skb->protocol use in case of accelerated vlan path") Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller