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

write to 0xffffffff8608c3f8 of 8 bytes by task 23694 on cpu 1:
 data_alloc+0x291/0x2c0 kernel/printk/printk_ringbuffer.c:1096
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2263
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2323
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2357
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2367
 batadv_check_known_mac_addr+0x147/0x180 net/batman-adv/hard-interface.c:526
 batadv_hard_if_event+0x4b0/0x1000 net/batman-adv/hard-interface.c:998
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:461
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1950
 call_netdevice_notifiers_extack net/core/dev.c:1988 [inline]
 call_netdevice_notifiers net/core/dev.c:2002 [inline]
 dev_set_mac_address+0x1ff/0x260 net/core/dev.c:8946
 dev_set_mac_address_user+0x31/0x50 net/core/dev.c:8960
 do_setlink+0x510/0x2480 net/core/rtnetlink.c:2839
 __rtnl_newlink net/core/rtnetlink.c:3680 [inline]
 rtnl_newlink+0x11a1/0x1690 net/core/rtnetlink.c:3727
 rtnetlink_rcv_msg+0x82e/0x8e0 net/core/rtnetlink.c:6595
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2559
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6613
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x5d3/0x6e0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 __sys_sendto+0x1e5/0x260 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2199
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffffffff8608c3f8 of 8 bytes by task 24665 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+0x235/0xb60 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2263
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2323
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2357
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2367
 __nla_validate_parse+0x1769/0x1ce0 lib/nlattr.c:647
 __nla_parse+0x40/0x60 lib/nlattr.c:732
 nla_parse_deprecated include/net/netlink.h:703 [inline]
 nfnetlink_rcv_batch net/netfilter/nfnetlink.c:512 [inline]
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:639 [inline]
 nfnetlink_rcv+0x9f4/0x13e0 net/netfilter/nfnetlink.c:657
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x58d/0x660 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x5d3/0x6e0 net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:745
 ____sys_sendmsg+0x312/0x410 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x280 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x00000000002fb708 -> 0x00000000003b2290

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24665 Comm: syz-executor.3 Tainted: G        W          6.8.0-syzkaller-11136-g66a27abac311 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
==================================================================
netlink: 48 bytes leftover after parsing attributes in process `syz-executor.3'.