==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff8687a108 of 8 bytes by task 21432 on cpu 1:
 data_alloc+0x27d/0x2b0 kernel/printk/printk_ringbuffer.c:1096
 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
 selinux_add_opt+0x230/0x270 security/selinux/hooks.c:1055
 selinux_fs_context_parse_param+0x7d/0xb0 security/selinux/hooks.c:2855
 security_fs_context_parse_param+0x65/0x130 security/security.c:1388
 vfs_parse_fs_param+0x103/0x2a0 fs/fs_context.c:138
 vfs_parse_fs_string+0x98/0xe0 fs/fs_context.c:188
 nfs23_parse_monolithic fs/nfs/fs_context.c:1230 [inline]
 nfs_fs_context_parse_monolithic+0xcd1/0x1280 fs/nfs/fs_context.c:1444
 parse_monolithic_mount_data+0x46/0x60 fs/fs_context.c:723
 do_new_mount+0x1da/0x680 fs/namespace.c:3898
 path_mount+0x4a4/0xb20 fs/namespace.c:4226
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4427
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4427
 x64_sys_call+0xd36/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffffffff8687a108 of 8 bytes by task 21433 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x221/0xaf0 kernel/printk/printk_ringbuffer.c:1619
 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
 validate_nla lib/nlattr.c:414 [inline]
 __nla_validate_parse+0x1227/0x1d00 lib/nlattr.c:635
 __nla_parse+0x40/0x60 lib/nlattr.c:732
 nla_parse_nested_deprecated include/net/netlink.h:1365 [inline]
 ctnl_timeout_parse_policy+0xa2/0x110 net/netfilter/nfnetlink_cttimeout.c:83
 cttimeout_new_timeout+0x1ef/0x460 net/netfilter/nfnetlink_cttimeout.c:164
 nfnetlink_rcv_msg+0x4c3/0x590 net/netfilter/nfnetlink.c:303
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2534
 nfnetlink_rcv+0x16b/0x1690 net/netfilter/nfnetlink.c:668
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x59e/0x670 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:727
 ____sys_sendmsg+0x31e/0x4e0 net/socket.c:2566
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2655
 x64_sys_call+0x2999/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:47
 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

value changed: 0xffffffffffff46f8 -> 0x000000000009acb8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21433 Comm: syz.4.6074 Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
netlink: 'syz.4.6074': attribute type 1 has an invalid length.
syz.4.6074 (21433) used greatest stack depth: 9160 bytes left