syzbot

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BUG: KCSAN: data-race in ip_check_mc_rcu / ip_mc_del1_src

write to 0xffff888023953190 of 8 bytes by task 15710 on cpu 0:
 ip_mc_del1_src+0x1be/0x410 net/ipv4/igmp.c:1871
 ip_mc_del_src+0x295/0x4c0 net/ipv4/igmp.c:1925
 ip_mc_leave_src net/ipv4/igmp.c:2231 [inline]
 ip_mc_drop_socket+0xec/0x1f0 net/ipv4/igmp.c:2677
 inet_release+0x58/0x130 net/ipv4/af_inet.c:418
 __sock_release net/socket.c:597 [inline]
 sock_close+0x6c/0x150 net/socket.c:1256
 __fput+0x24e/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x17c/0x1b0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:294
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888023953190 of 8 bytes by task 15747 on cpu 1:
 ip_check_mc_rcu+0x142/0x220 net/ipv4/igmp.c:2715
 __mkroute_output+0x245/0xd30 net/ipv4/route.c:2400
 ip_route_output_key_hash_rcu+0x8f4/0x950 net/ipv4/route.c:2679
 ip_route_output_key_hash net/ipv4/route.c:2507 [inline]
 __ip_route_output_key include/net/route.h:126 [inline]
 ip_route_output_flow+0xaf/0x160 net/ipv4/route.c:2768
 udp_sendmsg+0x100a/0x1560 net/ipv4/udp.c:1200
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg net/socket.c:2515 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2515
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15747 Comm: syz-executor.2 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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