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

write to 0xffffffff86ec5da0 of 8 bytes by task 17376 on cpu 1:
 data_alloc+0x216/0x2c0 kernel/printk/printk_ringbuffer.c:1074
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2322
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2332
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x42e/0x510 arch/x86/kernel/dumpstack.c:285
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xda/0x130 lib/dump_stack.c:106
 dump_stack+0x15/0x20 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x21f/0x230 lib/fault-inject.c:153
 should_fail+0xb/0x10 lib/fault-inject.c:163
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _copy_from_user+0x1e/0xd0 lib/usercopy.c:15
 copy_from_user include/linux/uaccess.h:183 [inline]
 copy_msghdr_from_user+0x54/0x2a0 net/socket.c:2488
 recvmsg_copy_msghdr net/socket.c:2743 [inline]
 ___sys_recvmsg net/socket.c:2815 [inline]
 do_recvmmsg+0x290/0x720 net/socket.c:2913
 __sys_recvmmsg net/socket.c:2992 [inline]
 __do_sys_recvmmsg net/socket.c:3015 [inline]
 __se_sys_recvmmsg net/socket.c:3008 [inline]
 __x64_sys_recvmmsg+0xe2/0x160 net/socket.c:3008
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86ec5da0 of 8 bytes by task 17400 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2322
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2332
 validate_nla lib/nlattr.c:397 [inline]
 __nla_validate_parse+0x13a3/0x1bc0 lib/nlattr.c:609
 validate_nla lib/nlattr.c:486 [inline]
 __nla_validate_parse+0x710/0x1bc0 lib/nlattr.c:609
 __nla_parse+0x40/0x50 lib/nlattr.c:706
 __nlmsg_parse include/net/netlink.h:745 [inline]
 genl_family_rcv_msg_attrs_parse+0x148/0x1a0 net/netlink/genetlink.c:801
 genl_family_rcv_msg_doit net/netlink/genetlink.c:949 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
 genl_rcv_msg+0x470/0x6a0 net/netlink/genetlink.c:1066
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2545
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1075
 netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
 netlink_unicast+0x589/0x650 net/netlink/af_netlink.c:1368
 netlink_sendmsg+0x66e/0x770 net/netlink/af_netlink.c:1910
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2558
 ___sys_sendmsg net/socket.c:2612 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2641
 __do_sys_sendmsg net/socket.c:2650 [inline]
 __se_sys_sendmsg net/socket.c:2648 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000001000075b4 -> 0x000000010000870d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17400 Comm: syz-executor.5 Not tainted 6.6.0-rc6-syzkaller-00045-g7cf4bea77ab6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
==================================================================