syzbot

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BUG: KCSAN: data-race in dccp_rcv_reset / sock_alloc_send_pskb

write to 0xffff8880a26897f0 of 4 bytes by interrupt on cpu 0:
 dccp_rcv_reset+0x119/0x1d0 net/dccp/input.c:149
 __dccp_rcv_established.isra.0+0x165/0x210 net/dccp/input.c:309
 dccp_rcv_established net/dccp/input.c:376 [inline]
 dccp_rcv_established+0x9c/0xc0 net/dccp/input.c:364
 dccp_v4_do_rcv+0xce/0x100 net/dccp/ipv4.c:655
 sk_backlog_rcv include/net/sock.h:938 [inline]
 __sk_receive_skb+0x1b5/0x580 net/core/sock.c:519
 dccp_v4_rcv+0x99f/0xf9b net/dccp/ipv4.c:876
 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x123/0x160 net/ipv4/ip_input.c:428
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:538
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5198
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5312
 process_backlog+0x216/0x4c0 net/core/dev.c:6144
 napi_poll net/core/dev.c:6582 [inline]
 net_rx_action+0x3ae/0xa90 net/core/dev.c:6650
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082
 do_softirq.part.0+0x6b/0x80 kernel/softirq.c:337
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x76/0x80 kernel/softirq.c:189
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 inet_csk_listen_stop+0x26c/0x7d0 net/ipv4/inet_connection_sock.c:1001
 dccp_close+0x72c/0x8f0 net/dccp/proto.c:1011
 inet_release+0x86/0x100 net/ipv4/af_inet.c:427
 inet6_release+0x4a/0x70 net/ipv6/af_inet6.c:470
 __sock_release+0x85/0x160 net/socket.c:605
 sock_close+0x24/0x30 net/socket.c:1283
 __fput+0x1e1/0x520 fs/file_table.c:280
 ____fput+0x1f/0x30 fs/file_table.c:313
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a26897f0 of 4 bytes by task 2480 on cpu 1:
 sock_error include/net/sock.h:2156 [inline]
 sock_alloc_send_pskb+0xc2/0x530 net/core/sock.c:2222
 sock_alloc_send_skb+0x3b/0x50 net/core/sock.c:2259
 dccp_sendmsg+0x15c/0x7c0 net/dccp/proto.c:786
 inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:672
 ____sys_sendmsg+0x212/0x4d0 net/socket.c:2343
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2397
 __sys_sendmmsg+0x123/0x350 net/socket.c:2487
 __do_sys_sendmmsg net/socket.c:2516 [inline]
 __se_sys_sendmmsg net/socket.c:2513 [inline]
 __x64_sys_sendmmsg+0x64/0x80 net/socket.c:2513
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2480 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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