================================================================== BUG: KCSAN: data-race in __process_echoes / n_tty_write write to 0xffffc90000337278 of 8 bytes by task 2674 on cpu 0: __process_echoes+0x607/0x660 drivers/tty/n_tty.c:765 flush_echoes drivers/tty/n_tty.c:826 [inline] __receive_buf drivers/tty/n_tty.c:1645 [inline] n_tty_receive_buf_common+0x1ba4/0x1e20 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 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:39 receive_buf drivers/tty/tty_buffer.c:481 [inline] flush_to_ldisc+0x1c5/0x2c0 drivers/tty/tty_buffer.c:533 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276 worker_thread+0x636/0xae0 kernel/workqueue.c:2422 kthread+0x1d0/0x1f0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 read to 0xffffc90000337278 of 8 bytes by task 12203 on cpu 1: process_echoes drivers/tty/n_tty.c:803 [inline] n_tty_write+0x147/0xaf0 drivers/tty/n_tty.c:2340 do_tty_write drivers/tty/tty_io.c:1043 [inline] file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1133 tty_write+0x24/0x30 drivers/tty/tty_io.c:1140 call_write_iter include/linux/fs.h:2114 [inline] do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740 do_iter_write+0x112/0x4c0 fs/read_write.c:866 vfs_writev fs/read_write.c:939 [inline] do_writev+0x1e0/0x400 fs/read_write.c:982 __do_sys_writev fs/read_write.c:1055 [inline] __se_sys_writev fs/read_write.c:1052 [inline] __x64_sys_writev+0x41/0x50 fs/read_write.c:1052 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x000000000000037f -> 0x0000000000000380 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 12203 Comm: syz-executor.2 Tainted: G W 5.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== FAULT_INJECTION: forcing a failure. name fail_usercopy, interval 1, probability 0, space 0, times 0 CPU: 1 PID: 12203 Comm: syz-executor.2 Tainted: G W 5.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x137/0x19d lib/dump_stack.c:120 fail_dump lib/fault-inject.c:52 [inline] should_fail+0x23c/0x250 lib/fault-inject.c:146 should_fail_usercopy+0x16/0x20 lib/fault-inject-usercopy.c:37 copyin lib/iov_iter.c:197 [inline] _copy_from_iter+0x179/0xba0 lib/iov_iter.c:809 copy_from_iter include/linux/uio.h:154 [inline] do_tty_write drivers/tty/tty_io.c:1040 [inline] file_tty_write+0x3d1/0x660 drivers/tty/tty_io.c:1133 tty_write+0x24/0x30 drivers/tty/tty_io.c:1140 call_write_iter include/linux/fs.h:2114 [inline] do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740 do_iter_write+0x112/0x4c0 fs/read_write.c:866 vfs_writev fs/read_write.c:939 [inline] do_writev+0x1e0/0x400 fs/read_write.c:982 __do_sys_writev fs/read_write.c:1055 [inline] __se_sys_writev fs/read_write.c:1052 [inline] __x64_sys_writev+0x41/0x50 fs/read_write.c:1052 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665d9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff9a3f9d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9 RDX: 0000000000000001 RSI: 00000000200005c0 RDI: 0000000000000003 RBP: 00007ff9a3f9d1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007fff62cd99ff R14: 00007ff9a3f9d300 R15: 0000000000022000