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BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88b893ca of 1 bytes by task 29 on cpu 0:
 string_nocheck lib/vsprintf.c:650 [inline]
 string+0x16c/0x210 lib/vsprintf.c:728
 vsnprintf+0xa09/0xe30 lib/vsprintf.c:2824
 vscnprintf+0x42/0x90 lib/vsprintf.c:2930
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2165
 vprintk_store+0x570/0x810 kernel/printk/printk.c:2279
 vprintk_emit+0x13a/0x610 kernel/printk/printk.c:2329
 vprintk_deferred kernel/printk/printk.c:4058 [inline]
 _printk_deferred+0x83/0xb0 kernel/printk/printk.c:4067
 ___ratelimit+0x297/0x2b0 lib/ratelimit.c:56
 __printk_ratelimit+0x1c/0x30 kernel/printk/printk.c:4083
 kauditd_printk_skb kernel/audit.c:545 [inline]
 kauditd_hold_skb+0x61/0x1b0 kernel/audit.c:581
 kauditd_send_queue+0x288/0x2e0 kernel/audit.c:766
 kauditd_thread+0x42a/0x650 kernel/audit.c:890
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffffffff88b893c8 of 8 bytes by task 15640 on cpu 1:
 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:2269
 vprintk_emit+0x13a/0x610 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 __nla_validate_parse+0x1881/0x1e30 lib/nlattr.c:647
 __nla_parse+0x40/0x60 lib/nlattr.c:732
 __nlmsg_parse include/net/netlink.h:761 [inline]
 nlmsg_parse_deprecated include/net/netlink.h:802 [inline]
 xfrm_user_rcv_msg+0x396/0x5c0 net/xfrm/xfrm_user.c:3298
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2550
 xfrm_netlink_rcv+0x47/0x60 net/xfrm/xfrm_user.c:3337
 netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
 netlink_unicast+0x599/0x670 net/netlink/af_netlink.c:1357
 netlink_sendmsg+0x5cc/0x6e0 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2603
 ___sys_sendmsg net/socket.c:2657 [inline]
 __sys_sendmsg+0x1dd/0x270 net/socket.c:2686
 __do_sys_sendmsg net/socket.c:2695 [inline]
 __se_sys_sendmsg net/socket.c:2693 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2693
 x64_sys_call+0x2689/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000ffffe7eb -> 0x5f6474696475616b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15640 Comm: syz.2.592 Tainted: G        W          6.11.0-syzkaller-02520-gadfc3ded5c33 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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