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

write to 0xffffffff86d7ca5c of 1 bytes by task 16340 on cpu 1:
 vsnprintf+0xe8f/0xed0
 vscnprintf+0x29/0x80 lib/vsprintf.c:2908
 printk_sprint kernel/printk/printk.c:2076 [inline]
 vprintk_store+0x638/0xbb0 kernel/printk/printk.c:2186
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 sctp_getsockopt_maxburst net/sctp/socket.c:6830 [inline]
 sctp_getsockopt+0x53bf/0x97f0 net/sctp/socket.c:8149
 sock_common_getsockopt+0x53/0x60 net/core/sock.c:3451
 __sys_getsockopt+0x171/0x1d0 net/socket.c:2220
 __do_sys_getsockopt net/socket.c:2235 [inline]
 __se_sys_getsockopt net/socket.c:2232 [inline]
 __x64_sys_getsockopt+0x62/0x70 net/socket.c:2232
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff86d7ca58 of 8 bytes by task 24 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x138/0x470 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x920/0xbf0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x560/0xbb0 kernel/printk/printk.c:2176
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 kauditd_printk_skb kernel/audit.c:538 [inline]
 kauditd_hold_skb+0x12d/0x140 kernel/audit.c:571
 kauditd_send_queue+0x206/0x2e0 kernel/audit.c:734
 kauditd_thread+0x425/0x6f0 kernel/audit.c:860
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x00000000fffff23a -> 0x000000000a646165

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24 Comm: kauditd Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
audit: type=1400 audit(1637892352.268:329): avc:  denied  { ioctl } for  pid=16515 comm="syz-executor.2" path="socket:[61627]" dev="sockfs" ino=61627 ioctlcmd=0x8933 scontext=root:sysadm_r:sysadm_t tcontext=root:sysadm_r:sysadm_t tclass=sctp_socket permissive=1