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BUG: KCSAN: data-race in kcm_rfree / unreserve_rx_kcm

write to 0xffff88812f2df7b8 of 8 bytes by task 1830 on cpu 1:
 unreserve_rx_kcm+0x72/0x1e0 net/kcm/kcmsock.c:312
 kcm_rcv_strparser+0x2d3/0x3d0 net/kcm/kcmsock.c:372
 __strp_recv+0x699/0xf00 net/strparser/strparser.c:301
 strp_recv+0x6d/0x80 net/strparser/strparser.c:335
 tcp_read_sock+0x27e/0x8b0 net/ipv4/tcp.c:1643
 strp_read_sock net/strparser/strparser.c:358 [inline]
 do_strp_work net/strparser/strparser.c:406 [inline]
 strp_work+0xe8/0x180 net/strparser/strparser.c:415
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff88812f2df7b8 of 8 bytes by task 4645 on cpu 0:
 kcm_rfree+0x121/0x200 net/kcm/kcmsock.c:180
 skb_release_head_state+0xb3/0x170 net/core/skbuff.c:729
 skb_release_all net/core/skbuff.c:740 [inline]
 __kfree_skb+0x14/0x150 net/core/skbuff.c:756
 kfree_skb+0x4d/0x160 net/core/skbuff.c:774
 kcm_recvmsg+0x245/0x2e0 net/kcm/kcmsock.c:1160
 ____sys_recvmsg+0x16c/0x320
 ___sys_recvmsg net/socket.c:2670 [inline]
 do_recvmmsg+0x3f5/0xae0 net/socket.c:2764
 __sys_recvmmsg net/socket.c:2843 [inline]
 __do_sys_recvmmsg net/socket.c:2866 [inline]
 __se_sys_recvmmsg net/socket.c:2859 [inline]
 __x64_sys_recvmmsg+0xde/0x160 net/socket.c:2859
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888138771e00 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4645 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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