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

write to 0xffffffff866d7278 of 8 bytes by task 28980 on cpu 0:
 prb_reserve+0x740/0xb60
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 batadv_check_known_mac_addr+0x153/0x180 net/batman-adv/hard-interface.c:528
 batadv_hard_if_event+0x4b9/0xfb0 net/batman-adv/hard-interface.c:998
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1996
 call_netdevice_notifiers_extack net/core/dev.c:2034 [inline]
 call_netdevice_notifiers net/core/dev.c:2048 [inline]
 dev_set_mac_address+0x1ff/0x260 net/core/dev.c:9212
 dev_set_mac_address_user+0x31/0x50 net/core/dev.c:9226
 do_setlink+0x3ec/0x22c0 net/core/rtnetlink.c:3064
 rtnl_changelink net/core/rtnetlink.c:3723 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3875 [inline]
 rtnl_newlink+0xde9/0x1250 net/core/rtnetlink.c:4012
 rtnetlink_rcv_msg+0x651/0x710 net/core/rtnetlink.c:6922
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2542
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6949
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x599/0x670 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x5cc/0x6e0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:726
 __sys_sendto+0x1a8/0x230 net/socket.c:2197
 __do_sys_sendto net/socket.c:2204 [inline]
 __se_sys_sendto net/socket.c:2200 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2200
 x64_sys_call+0x29fa/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff866d7278 of 8 bytes by task 2988 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1ec/0xba0 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3d/0x60 kernel/printk/printk_ringbuffer.c:2182
 syslog_print+0x157/0x760 kernel/printk/printk.c:1633
 do_syslog+0x3a1/0x7f0 kernel/printk/printk.c:1785
 __do_sys_syslog kernel/printk/printk.c:1877 [inline]
 __se_sys_syslog kernel/printk/printk.c:1875 [inline]
 __x64_sys_syslog+0x43/0x50 kernel/printk/printk.c:1875
 x64_sys_call+0x29be/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:104
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000c35 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2988 Comm: klogd Not tainted 6.13.0-rc3-syzkaller-00193-ge9b8ffafd20a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
==================================================================