==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88ec2870 of 1 bytes by task 29 on cpu 1:
 string_nocheck lib/vsprintf.c:658 [inline]
 string+0x187/0x220 lib/vsprintf.c:736
 vsnprintf+0x532/0x860 lib/vsprintf.c:2947
 vscnprintf+0x41/0x90 lib/vsprintf.c:3012
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2192
 vprintk_store+0x568/0x830 kernel/printk/printk.c:2312
 vprintk_emit+0x15a/0x5c0 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
 kauditd_printk_skb kernel/audit.c:583 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:618
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:803
 kauditd_thread+0x442/0x680 kernel/audit.c:927
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffffffff88ec2870 of 8 bytes by task 9177 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d7/0xad0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x53c/0x830 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x5c0 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
 isofs_read_inode fs/isofs/inode.c:1376 [inline]
 __isofs_iget+0xfb0/0x1100 fs/isofs/inode.c:1524
 isofs_iget fs/isofs/isofs.h:135 [inline]
 isofs_get_blocks+0x185/0x490 fs/isofs/inode.c:1069
 isofs_get_block fs/isofs/inode.c:1122 [inline]
 isofs_bmap fs/isofs/inode.c:1133 [inline]
 isofs_bread+0x5b/0x100 fs/isofs/inode.c:1141
 isofs_find_entry fs/isofs/namei.c:59 [inline]
 isofs_lookup+0x1a8/0x930 fs/isofs/namei.c:165
 __lookup_slow+0x193/0x250 fs/namei.c:1858
 lookup_slow+0x3c/0x60 fs/namei.c:1875
 walk_component fs/namei.c:2221 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x2f7/0x500 fs/namei.c:2746
 filename_lookup+0x147/0x340 fs/namei.c:2775
 kern_path+0x3b/0x130 fs/namei.c:2987
 unix_find_bsd net/unix/af_unix.c:1215 [inline]
 unix_find_other+0xe9/0x700 net/unix/af_unix.c:1277
 unix_dgram_sendmsg+0x597/0xfd0 net/unix/af_unix.c:2151
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 ____sys_sendmsg+0x345/0x4a0 net/socket.c:2592
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2646
 __sys_sendmmsg+0x178/0x300 net/socket.c:2735
 __do_sys_sendmmsg net/socket.c:2762 [inline]
 __se_sys_sendmmsg net/socket.c:2759 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2759
 x64_sys_call+0x1e28/0x3000 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000ffffe8b7 -> 0x3635333638363637

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9177 Comm: syz.3.1892 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
syz.3.1892 (9177) used greatest stack depth: 9000 bytes left