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BUG: KCSAN: data-race in xfrm_sk_policy_insert / xfrm_sk_policy_insert

write to 0xffffffff87005938 of 4 bytes by task 29466 on cpu 0:
 xfrm_gen_index net/xfrm/xfrm_policy.c:1385 [inline]
 xfrm_sk_policy_insert+0x262/0x640 net/xfrm/xfrm_policy.c:2347
 xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639
 do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943
 ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012
 rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054
 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697
 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263
 __do_sys_setsockopt net/socket.c:2274 [inline]
 __se_sys_setsockopt net/socket.c:2271 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff87005938 of 4 bytes by task 29460 on cpu 1:
 xfrm_sk_policy_insert+0x13e/0x640
 xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639
 do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943
 ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012
 rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054
 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697
 __sys_setsockopt+0x1c9/0x230 net/socket.c:2263
 __do_sys_setsockopt net/socket.c:2274 [inline]
 __se_sys_setsockopt net/socket.c:2271 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2271
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00006ad8 -> 0x00006b18

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29460 Comm: syz-executor.1 Not tainted 6.5.0-rc5-syzkaller-00243-g9106536c1aa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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