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BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff8839241a of 1 bytes by task 22050 on cpu 1:
 string_nocheck lib/vsprintf.c:650 [inline]
 string+0x16c/0x210 lib/vsprintf.c:728
 vsnprintf+0xa09/0xe30 lib/vsprintf.c:2824
 va_format lib/vsprintf.c:1683 [inline]
 pointer+0x8a1/0xd20 lib/vsprintf.c:2455
 vsnprintf+0x861/0xe30 lib/vsprintf.c:2828
 vscnprintf+0x42/0x90 lib/vsprintf.c:2930
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2159
 vprintk_store+0x570/0x810 kernel/printk/printk.c:2273
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2323
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2357
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2367
 __netdev_printk+0x2d1/0x3e0 net/core/dev.c:11507
 netdev_info+0x99/0xc0 net/core/dev.c:11554
 __dev_set_allmulti+0x190/0x290 net/core/dev.c:8546
 dev_set_allmulti+0x1f/0x30 net/core/dev.c:8572
 nbp_delete_promisc net/bridge/br_if.c:252 [inline]
 del_nbp+0x68/0x770 net/bridge/br_if.c:340
 br_dev_delete+0x4e/0xe0 net/bridge/br_if.c:386
 br_net_exit_batch_rtnl+0xca/0x170 net/bridge/br.c:369
 cleanup_net+0x3df/0x830 net/core/net_namespace.c:630
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
 worker_thread+0x526/0x730 kernel/workqueue.c:3416
 kthread+0x1d1/0x210 kernel/kthread.c:388
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

read to 0xffffffff88392418 of 8 bytes by task 21378 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2263
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2323
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2357
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2367
 rds_bind+0xb13/0xdf0 net/rds/bind.c:258
 __sys_bind+0x15b/0x1d0 net/socket.c:1847
 __do_sys_bind net/socket.c:1858 [inline]
 __se_sys_bind net/socket.c:1856 [inline]
 __x64_sys_bind+0x41/0x50 net/socket.c:1856
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0000000100004daa -> 0x6c6c61207466656c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21378 Comm: syz-executor.2 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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