audit: type=1326 audit(1764835828.156:2213): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6653 comm="syz.7.700" exe="/root/syz-executor" sig=0 arch=c000003e syscall=321 compat=0 ip=0x7f87f20ef749 code=0x7ffc0000
audit: type=1326 audit(1764835828.156:2214): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6653 comm="syz.7.700" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f87f20ef749 code=0x7ffc0000
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88e871f0 of 1 bytes by task 6667 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+0x599/0x860 kernel/printk/printk.c:2312
 vprintk_emit+0x15a/0x610 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
 __ext4_msg+0x18f/0x1a0 fs/ext4/super.c:990
 ext4_fill_super+0x2fbd/0x3800 fs/ext4/super.c:5751
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1699
 get_tree_bdev+0x1f/0x30 fs/super.c:1722
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768
 vfs_get_tree+0x57/0x1d0 fs/super.c:1759
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x24d/0x6a0 fs/namespace.c:3712
 path_mount+0x4ab/0xb80 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201
 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88e871f0 of 8 bytes by task 29 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+0x964/0xb60 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x610 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

value changed: 0x00000000ffffe29d -> 0x662d345458453601

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 29 Comm: kauditd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
audit: type=1326 audit(1764835828.156:2215): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6653 comm="syz.7.700" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7f87f20ef749 code=0x7ffc0000
audit: type=1326 audit(1764835828.186:2216): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6651 comm="syz.9.699" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fce27f7f749 code=0x7ffc0000
audit: type=1326 audit(1764835828.186:2217): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6651 comm="syz.9.699" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fce27f7f749 code=0x7ffc0000
audit: type=1326 audit(1764835828.196:2218): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6651 comm="syz.9.699" exe="/root/syz-executor" sig=0 arch=c000003e syscall=258 compat=0 ip=0x7fce27f7f749 code=0x7ffc0000
audit: type=1326 audit(1764835828.196:2219): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6651 comm="syz.9.699" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fce27f7f749 code=0x7ffc0000
audit: type=1326 audit(1764835828.196:2220): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=6651 comm="syz.9.699" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fce27f7f749 code=0x7ffc0000