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BUG: KCSAN: data-race in n_tty_receive_buf_common / n_tty_receive_buf_common

write to 0xffffc90000335000 of 8 bytes by task 1696 on cpu 0:
 put_tty_queue drivers/tty/n_tty.c:316 [inline]
 n_tty_receive_buf_raw drivers/tty/n_tty.c:1538 [inline]
 __receive_buf drivers/tty/n_tty.c:1627 [inline]
 n_tty_receive_buf_common+0xa41/0x1e20 drivers/tty/n_tty.c:1740
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1769
 tiocsti drivers/tty/tty_io.c:2315 [inline]
 tty_ioctl+0x968/0x1120 drivers/tty/tty_io.c:2721
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffc90000335000 of 8 bytes by task 14132 on cpu 1:
 put_tty_queue drivers/tty/n_tty.c:315 [inline]
 n_tty_receive_buf_raw drivers/tty/n_tty.c:1538 [inline]
 __receive_buf drivers/tty/n_tty.c:1627 [inline]
 n_tty_receive_buf_common+0xa14/0x1e20 drivers/tty/n_tty.c:1740
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1775
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:461
 paste_selection+0x250/0x340 drivers/tty/vt/selection.c:408
 tioclinux+0xe5/0x450 drivers/tty/vt/vt.c:3164
 vt_ioctl+0x26e/0x2060 drivers/tty/vt/vt_ioctl.c:760
 tty_ioctl+0xa24/0x1120 drivers/tty/tty_io.c:2805
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14132 Comm: syz-executor.1 Tainted: G        W         5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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