syzbot

==================================================================
BUG: KCSAN: data-race in tipc_group_cong / tipc_poll

write to 0xffff888110f71ff8 of 1 bytes by task 19441 on cpu 0:
 tipc_group_cong+0x191/0x2b0 net/tipc/group.c:434
 tipc_group_bc_cong+0xeb/0x110 net/tipc/group.c:467
 tipc_send_group_bcast+0x1d6/0x700 net/tipc/socket.c:1097
 __tipc_sendmsg+0x1a0/0x1c90 net/tipc/socket.c:-1
 tipc_sendmsg+0x3e/0x60 net/tipc/socket.c:1399
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:727
 ____sys_sendmsg+0x350/0x4e0 net/socket.c:2566
 ___sys_sendmsg net/socket.c:2620 [inline]
 __sys_sendmmsg+0x22a/0x4b0 net/socket.c:2709
 __do_sys_sendmmsg net/socket.c:2736 [inline]
 __se_sys_sendmmsg net/socket.c:2733 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2733
 x64_sys_call+0x2b53/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:308
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888110f71ff8 of 1 bytes by task 19437 on cpu 1:
 tipc_poll+0x11e/0x360 net/tipc/socket.c:815
 sock_poll+0x22d/0x250 net/socket.c:1379
 vfs_poll include/linux/poll.h:82 [inline]
 select_poll_one fs/select.c:480 [inline]
 do_select+0x92b/0xfc0 fs/select.c:536
 core_sys_select+0x4c3/0x6d0 fs/select.c:677
 do_pselect fs/select.c:759 [inline]
 __do_sys_pselect6 fs/select.c:802 [inline]
 __se_sys_pselect6+0x212/0x270 fs/select.c:793
 __x64_sys_pselect6+0x78/0x90 fs/select.c:793
 x64_sys_call+0x1c26/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:271
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19437 Comm: syz.3.5829 Not tainted 6.15.0-rc1-syzkaller-00325-g7cdabafc0012 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================