syzbot

BUG: KCSAN: data-race in data_push_tail / symbol_string

write to 0xffffffff88e29840 of 1 bytes by task 5569 on cpu 0:
 string_nocheck lib/vsprintf.c:657 [inline]
 symbol_string+0x1ce/0x250 lib/vsprintf.c:1013
 pointer+0x60c/0xcf0 lib/vsprintf.c:2515
 vsnprintf+0x491/0x890 lib/vsprintf.c:2930
 vscnprintf+0x41/0x90 lib/vsprintf.c:2991
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 printk_stack_address arch/x86/kernel/dumpstack.c:70 [inline]
 show_trace_log_lvl+0x4e3/0x560 arch/x86/kernel/dumpstack.c:282
 __dump_stack+0x1d/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120
 dump_stack+0x15/0x1b lib/dump_stack.c:129
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x265/0x280 lib/fault-inject.c:174
 should_failslab+0x8c/0xb0 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4133 [inline]
 slab_alloc_node mm/slub.c:4209 [inline]
 kmem_cache_alloc_noprof+0x50/0x310 mm/slub.c:4236
 alloc_empty_file+0x76/0x200 fs/file_table.c:237
 path_openat+0x68/0x2170 fs/namei.c:4032
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_creat fs/open.c:1528 [inline]
 __se_sys_creat fs/open.c:1522 [inline]
 __x64_sys_creat+0x65/0x90 fs/open.c:1522
 x64_sys_call+0x2d94/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:86
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88e29840 of 8 bytes by task 5456 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4914
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4925
 __netdev_printk+0x35c/0x3e0 net/core/dev.c:12598
 netdev_info+0x9b/0xd0 net/core/dev.c:12653
 nsim_udp_tunnel_unset_port+0x18a/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+0x564/0x9c0 net/ipv4/udp_tunnel_nic.c:292
 udp_tunnel_nic_device_sync_work+0x5d/0x5f0 net/ipv4/udp_tunnel_nic.c:740
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:463
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000000ffffe371 -> 0x363778302b656c69

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5456 Comm: kworker/u8:27 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: udp_tunnel_nic udp_tunnel_nic_device_sync_work
==================================================================
netdevsim netdevsim0 netdevsim3: unset [1, 0] type 2 family 0 port 6081 - 0