audit: type=1400 audit(1752664271.528:36634): avc:  denied  { mounton } for  pid=8967 comm="syz.3.11213" path="/syzcgroup/unified/syz3" dev="cgroup2" ino=31 scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:cgroup_t tclass=dir permissive=1
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88e63ef0 of 1 bytes by task 8973 on cpu 0:
 string_nocheck lib/vsprintf.c:643 [inline]
 string+0x187/0x220 lib/vsprintf.c:721
 vsnprintf+0x532/0x890 lib/vsprintf.c:2874
 vscnprintf+0x41/0x90 lib/vsprintf.c:2939
 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
 dump_stack_print_info+0xee/0x1b0 lib/dump_stack.c:57
 __dump_stack+0x11/0x30 lib/dump_stack.c:93
 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_fail+0xb/0x20 lib/fault-inject.c:184
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _inline_copy_to_user include/linux/uaccess.h:193 [inline]
 _copy_to_user+0x20/0xa0 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:225 [inline]
 simple_read_from_buffer+0xb5/0x130 fs/libfs.c:1122
 proc_fail_nth_read+0x100/0x140 fs/proc/base.c:1488
 vfs_read+0x19d/0x6f0 fs/read_write.c:570
 ksys_read+0xda/0x1a0 fs/read_write.c:715
 __do_sys_read fs/read_write.c:724 [inline]
 __se_sys_read fs/read_write.c:722 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:722
 x64_sys_call+0x2d77/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:1
 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 0xffffffff88e63ef0 of 8 bytes by task 29 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
 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
 kauditd_printk_skb kernel/audit.c:546 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:581
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:766
 kauditd_thread+0x421/0x630 kernel/audit.c:890
 kthread+0x489/0x510 kernel/kthread.c:464
 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: 0x0000000100006877 -> 0x61353531672d3230

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29 Comm: kauditd Tainted: G        W           6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================