syzbot

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BUG: KCSAN: data-race in get_task_mm / ns_capable_common

read to 0xffff8880a751e124 of 4 bytes by task 8258 on cpu 0:
 get_task_mm+0x4f/0xa0 kernel/fork.c:1209
 get_task_cmdline fs/proc/base.c:346 [inline]
 proc_pid_cmdline_read+0x9d/0x6a0 fs/proc/base.c:366
 __vfs_read+0x67/0xc0 fs/read_write.c:425
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880a751e124 of 4 bytes by task 8070 on cpu 1:
 ns_capable_common+0x9f/0xc0 kernel/capability.c:377
 ns_capable+0x29/0x40 kernel/capability.c:396
 do_ebt_get_ctl+0x61/0x440 net/bridge/netfilter/ebtables.c:1487
 nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
 nf_getsockopt+0x71/0xb0 net/netfilter/nf_sockopt.c:122
 ip_getsockopt net/ipv4/ip_sockglue.c:1576 [inline]
 ip_getsockopt+0x118/0x160 net/ipv4/ip_sockglue.c:1556
 tcp_getsockopt net/ipv4/tcp.c:3688 [inline]
 tcp_getsockopt+0x7c/0xc0 net/ipv4/tcp.c:3682
 sock_common_getsockopt+0x67/0x90 net/core/sock.c:3110
 __sys_getsockopt+0xf1/0x210 net/socket.c:2129
 __do_sys_getsockopt net/socket.c:2144 [inline]
 __se_sys_getsockopt net/socket.c:2141 [inline]
 __x64_sys_getsockopt+0x70/0x90 net/socket.c:2141
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8070 Comm: syz-executor.5 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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