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BUG: KCSAN: data-race in xfrm_sk_policy_insert / xfrm_sk_policy_insert

write to 0xffffffff8419e590 of 4 bytes by task 2150 on cpu 1:
 xfrm_gen_index net/xfrm/xfrm_policy.c:1382 [inline]
 xfrm_sk_policy_insert+0xe2/0x600 net/xfrm/xfrm_policy.c:2269
 xfrm_user_policy+0x309/0x430 net/xfrm/xfrm_state.c:2442
 do_ipv6_setsockopt net/ipv6/ipv6_sockglue.c:940 [inline]
 ipv6_setsockopt+0xd77/0x34b0 net/ipv6/ipv6_sockglue.c:1003
 rawv6_setsockopt+0x1f5/0x3f0 net/ipv6/raw.c:1081
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3383
 __sys_setsockopt+0x18f/0x200 net/socket.c:2176
 __do_sys_setsockopt net/socket.c:2187 [inline]
 __se_sys_setsockopt net/socket.c:2184 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2184
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8419e590 of 4 bytes by task 2149 on cpu 0:
 xfrm_gen_index net/xfrm/xfrm_policy.c:1381 [inline]
 xfrm_sk_policy_insert+0xbe/0x600 net/xfrm/xfrm_policy.c:2269
 xfrm_user_policy+0x309/0x430 net/xfrm/xfrm_state.c:2442
 do_ipv6_setsockopt net/ipv6/ipv6_sockglue.c:940 [inline]
 ipv6_setsockopt+0xd77/0x34b0 net/ipv6/ipv6_sockglue.c:1003
 rawv6_setsockopt+0x1f5/0x3f0 net/ipv6/raw.c:1081
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3383
 __sys_setsockopt+0x18f/0x200 net/socket.c:2176
 __do_sys_setsockopt net/socket.c:2187 [inline]
 __se_sys_setsockopt net/socket.c:2184 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2184
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00004058 -> 0x00004060

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2149 Comm: syz-executor.1 Tainted: G        W         5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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