audit: type=1400 audit(2000008788.470:15194): avc:  denied  { mounton } for  pid=15853 comm="syz.0.3413" path="/syzcgroup/unified/syz0" dev="cgroup2" ino=77 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 / vsnprintf

write to 0xffffffff893b02c9 of 15 bytes by task 15854 on cpu 1:
 vsnprintf+0x2ce/0x860 lib/vsprintf.c:2899
 va_format lib/vsprintf.c:1723 [inline]
 pointer+0x821/0xcb0 lib/vsprintf.c:2569
 vsnprintf+0x491/0x860 lib/vsprintf.c:2952
 vscnprintf+0x41/0x90 lib/vsprintf.c:3013
 printk_sprint+0x30/0x2e0 kernel/printk/printk.c:2222
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2364
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 logfc+0x2d5/0x2e0 fs/fs_context.c:-1
 shmem_parse_one+0xa7b/0xbc0 mm/shmem.c:-1
 vfs_parse_fs_param+0x142/0x2a0 fs/fs_context.c:132
 vfs_parse_fs_qstr fs/fs_context.c:173 [inline]
 vfs_parse_fs_string include/linux/fs_context.h:142 [inline]
 vfs_parse_monolithic_sep+0x1e6/0x270 fs/fs_context.c:213
 shmem_parse_monolithic+0x24/0x30 mm/shmem.c:4804
 parse_monolithic_mount_data+0x46/0x60 fs/fs_context.c:520
 do_new_mount+0x24e/0x8d0 fs/namespace.c:3835
 path_mount+0x4d0/0xbc0 fs/namespace.c:4159
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff893b02d0 of 8 bytes by task 28 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+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 kauditd_printk_skb kernel/audit.c:587 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:622
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:807
 kauditd_thread+0x444/0x670 kernel/audit.c:931
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000000fffff4a6 -> 0x706d2720726f6620

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 28 Comm: kauditd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
audit: type=1400 audit(2000008788.838:15195): avc:  denied  { create } for  pid=15855 comm="syz.0.3414" scontext=root:sysadm_r:sysadm_t tcontext=root:sysadm_r:sysadm_t tclass=rose_socket permissive=1
audit: type=1400 audit(2000008789.373:15196): avc:  denied  { egress } for  pid=14 comm="ksoftirqd/0" saddr=fe80::a8aa:aaff:feaa:aa1b daddr=ff02::2 netif=gretap0 scontext=system_u:object_r:unlabeled_t tcontext=system_u:object_r:netif_t tclass=netif permissive=1
audit: type=1400 audit(2000008789.373:15197): avc:  denied  { sendto } for  pid=14 comm="ksoftirqd/0" saddr=fe80::a8aa:aaff:feaa:aa1b daddr=ff02::2 netif=gretap0 scontext=system_u:object_r:unlabeled_t tcontext=system_u:object_r:node_t tclass=node permissive=1