================================================================== BUG: KCSAN: data-race in data_alloc / prb_reserve write to 0xffffffff86881310 of 8 bytes by task 1051 on cpu 0: data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130 prb_reserve+0x964/0xb60 kernel/printk/printk_ringbuffer.c:1724 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2451 __nla_validate_parse+0x1738/0x1d00 lib/nlattr.c:647 __nla_parse+0x40/0x60 lib/nlattr.c:732 nla_parse_nested_deprecated include/net/netlink.h:1379 [inline] rtnl_newlink+0x7ac/0x1360 net/core/rtnetlink.c:4019 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x145/0x180 net/socket.c:742 ____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681 x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff86881310 of 8 bytes by task 1048 on cpu 1: desc_read kernel/printk/printk_ringbuffer.c:496 [inline] desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline] desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline] prb_reserve+0x249/0xb60 kernel/printk/printk_ringbuffer.c:1674 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4914 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4925 __netdev_printk+0x34b/0x370 net/core/dev.c:12901 netdev_info+0x9b/0xd0 net/core/dev.c:12956 nsim_udp_tunnel_unset_port+0x190/0x1b0 drivers/net/netdevsim/udp_tunnels.c:59 udp_tunnel_nic_device_sync_one net/ipv4/udp_tunnel_nic.c:-1 [inline] udp_tunnel_nic_device_sync_by_port net/ipv4/udp_tunnel_nic.c:249 [inline] __udp_tunnel_nic_device_sync+0x567/0x9c0 net/ipv4/udp_tunnel_nic.c:292 udp_tunnel_nic_flush+0x21b/0x300 net/ipv4/udp_tunnel_nic.c:694 udp_tunnel_nic_unregister net/ipv4/udp_tunnel_nic.c:901 [inline] udp_tunnel_nic_netdevice_event+0x8c0/0xd70 net/ipv4/udp_tunnel_nic.c:942 notifier_call_chain kernel/notifier.c:85 [inline] raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453 call_netdevice_notifiers_info net/core/dev.c:2230 [inline] call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] unregister_netdevice_many_notify+0xea0/0x16d0 net/core/dev.c:12381 unregister_netdevice_many net/core/dev.c:12444 [inline] unregister_netdevice_queue+0x1b8/0x1e0 net/core/dev.c:12258 unregister_netdevice include/linux/netdevice.h:3405 [inline] nsim_destroy+0xfa/0x2f0 drivers/net/netdevsim/netdev.c:1180 __nsim_dev_port_del+0xcf/0x110 drivers/net/netdevsim/dev.c:1528 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1540 [inline] nsim_dev_reload_destroy+0x1a3/0x2c0 drivers/net/netdevsim/dev.c:1763 nsim_dev_reload_down+0x67/0x80 drivers/net/netdevsim/dev.c:1038 devlink_reload+0xad/0x580 net/devlink/dev.c:461 devlink_nl_reload_doit+0x503/0x960 net/devlink/dev.c:584 genl_family_rcv_msg_doit+0x143/0x1b0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x422/0x460 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x145/0x180 net/socket.c:742 ____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681 x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000000b94f0 -> 0x00000000001572f0 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 1048 Comm: syz.2.9645 Tainted: G W syzkaller #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 ================================================================== netdevsim netdevsim2 eth2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 eth1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0 netdevsim netdevsim2 eth0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0