syzbot

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BUG: KCSAN: data-race in cake_change / cake_overhead

write to 0xffff88817904c28a of 2 bytes by task 490 on cpu 0:
 cake_change+0x3b8/0x890 net/sched/sch_cake.c:2631
 qdisc_change net/sched/sch_api.c:1416 [inline]
 tc_modify_qdisc+0xefc/0x1050 net/sched/sch_api.c:1746
 rtnetlink_rcv_msg+0x82e/0x8e0 net/core/rtnetlink.c:6595
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2559
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6613
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x5d3/0x6e0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x280 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff88817904c28a of 2 bytes by task 483 on cpu 1:
 cake_calc_overhead net/sched/sch_cake.c:1344 [inline]
 cake_overhead+0x77b/0x8d0 net/sched/sch_cake.c:1361
 cake_enqueue+0x108e/0x48a0 net/sched/sch_cake.c:1778
 dev_qdisc_enqueue net/core/dev.c:3726 [inline]
 __dev_xmit_skb net/core/dev.c:3817 [inline]
 __dev_queue_xmit+0x84d/0x1dd0 net/core/dev.c:4301
 dev_queue_xmit include/linux/netdevice.h:3091 [inline]
 neigh_hh_output include/net/neighbour.h:526 [inline]
 neigh_output include/net/neighbour.h:540 [inline]
 ip6_finish_output2+0xa47/0xd10 net/ipv6/ip6_output.c:137
 ip6_finish_output+0x438/0x540 net/ipv6/ip6_output.c:222
 NF_HOOK_COND include/linux/netfilter.h:303 [inline]
 ip6_output+0xeb/0x220 net/ipv6/ip6_output.c:243
 dst_output include/net/dst.h:450 [inline]
 ip6_local_out+0x76/0xd0 net/ipv6/output_core.c:155
 ip6_send_skb net/ipv6/ip6_output.c:1955 [inline]
 ip6_push_pending_frames+0xbb/0x180 net/ipv6/ip6_output.c:1975
 rawv6_push_pending_frames+0x45d/0x4d0 net/ipv6/raw.c:588
 rawv6_sendmsg+0xe34/0xf40 net/ipv6/raw.c:926
 inet_sendmsg+0xc5/0xd0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x102/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmmsg+0x269/0x500 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2750
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0036 -> 0xffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 483 Comm: syz-executor.3 Not tainted 6.8.0-syzkaller-13161-gbfa8f18691ed #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
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