syzbot

syz.2.160 (4130) used greatest stack depth: 10312 bytes left
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BUG: KCSAN: data-race in console_flush_all / console_flush_all

write to 0xffffffff86a20b48 of 8 bytes by task 4153 on cpu 1:
 console_emit_next_record kernel/printk/printk.c:3099 [inline]
 console_flush_all+0x35a/0x730 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xa1/0x330 kernel/printk/printk.c:3325
 vprintk_emit+0x388/0x650 kernel/printk/printk.c:2450
 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
 chnl_net_open+0x2a9/0x560 net/caif/chnl_net.c:260
 __dev_open+0x2d2/0x530 net/core/dev.c:1682
 __dev_change_flags+0x163/0x400 net/core/dev.c:9532
 netif_change_flags+0x5a/0xd0 net/core/dev.c:9595
 do_setlink+0x9d2/0x2810 net/core/rtnetlink.c:3143
 rtnl_group_changelink net/core/rtnetlink.c:3775 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3929 [inline]
 rtnl_newlink+0xd8b/0x12d0 net/core/rtnetlink.c:4057
 rtnetlink_rcv_msg+0x5fb/0x6d0 net/core/rtnetlink.c:6946
 netlink_rcv_skb+0x120/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6973
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:729
 ____sys_sendmsg+0x31e/0x4e0 net/socket.c:2614
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2703
 x64_sys_call+0x191e/0x2ff0 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

read to 0xffffffff86a20b48 of 8 bytes by task 4130 on cpu 0:
 console_flush_all+0x563/0x730 kernel/printk/printk.c:3227
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xa1/0x330 kernel/printk/printk.c:3325
 vprintk_emit+0x388/0x650 kernel/printk/printk.c:2450
 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
 check_stack_usage kernel/exit.c:853 [inline]
 do_exit+0x10c6/0x15c0 kernel/exit.c:996
 do_group_exit+0xff/0x140 kernel/exit.c:1102
 get_signal+0xe59/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000901 -> 0x0000000000000902

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4130 Comm: syz.2.160 Not tainted 6.17.0-rc1-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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