syzbot


KCSAN: data-race in pty_close / pty_flush_buffer

Status: auto-closed as invalid on 2022/08/30 11:39
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 158d, last: 125d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in pty_close / pty_flush_buffer

write to 0xffff8881383181d9 of 1 bytes by task 2947 on cpu 0:
 pty_close+0x120/0x280 drivers/tty/pty.c:61
 tty_release+0x255/0x9d0 drivers/tty/tty_io.c:1758
 __fput+0x292/0x510 fs/file_table.c:317
 ____fput+0x11/0x20 fs/file_table.c:350
 task_work_run+0x8e/0x110 kernel/task_work.c:177
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x130 kernel/entry/common.c:169
 exit_to_user_mode_prepare kernel/entry/common.c:201 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x6a/0x90 kernel/entry/common.c:294
 do_syscall_64+0x37/0x70 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881383181d9 of 1 bytes by task 2958 on cpu 1:
 pty_flush_buffer+0x40/0xc0 drivers/tty/pty.c:212
 tty_driver_flush_buffer+0x3a/0x50 drivers/tty/tty_ioctl.c:95
 tty_ldisc_hangup+0x98/0x470 drivers/tty/tty_ldisc.c:695
 __tty_hangup+0x438/0x5b0 drivers/tty/tty_io.c:637
 tty_vhangup drivers/tty/tty_io.c:707 [inline]
 tty_ioctl+0x49f/0x970 drivers/tty/tty_io.c:2718
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2958 Comm: syz-executor.2 Not tainted 5.19.0-rc8-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
==================================================================

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/07/26 11:35 upstream e0dccc3b76fb 279b89c2 .config log report info KCSAN: data-race in pty_close / pty_flush_buffer
ci2-upstream-kcsan-gce 2022/06/22 17:20 upstream ca1fdab7fd27 912f5df7 .config log report info KCSAN: data-race in pty_close / pty_flush_buffer
* Struck through repros no longer work on HEAD.