syzbot


KCSAN: data-race in __process_echoes / n_tty_write (4)

Status: auto-closed as invalid on 2021/08/15 21:06
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 449d, last: 449d
similar bugs (4):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __process_echoes / n_tty_write 3 778d 820d 0/24 auto-closed as invalid on 2020/09/20 17:41
upstream KCSAN: data-race in __process_echoes / n_tty_write (3) 7 491d 557d 0/24 auto-closed as invalid on 2021/07/04 10:36
upstream KCSAN: data-race in __process_echoes / n_tty_write (2) 4 646d 665d 0/24 auto-closed as invalid on 2021/01/30 23:25
upstream KCSAN: data-race in __process_echoes / n_tty_write (5) 1 369d 369d 0/24 auto-closed as invalid on 2021/11/04 02:47

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __process_echoes / n_tty_write

write to 0xffffc90006703278 of 8 bytes by task 2900 on cpu 1:
 __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:1579 [inline]
 n_tty_receive_buf_common+0x4c38/0x4e70 drivers/tty/n_tty.c:1674
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1709
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:471
 paste_selection+0x215/0x300 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_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffc90006703278 of 8 bytes by task 2907 on cpu 0:
 process_echoes drivers/tty/n_tty.c:803 [inline]
 n_tty_write+0x147/0xaf0 drivers/tty/n_tty.c:2274
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1110
 tty_write+0x24/0x30 drivers/tty/tty_io.c:1131
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000003132 -> 0x0000000000003138

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2907 Comm: syz-executor.0 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/07/11 21:04 upstream 98f7fdced2e0 8f5a7b8c .config log report info KCSAN: data-race in __process_echoes / n_tty_write
* Struck through repros no longer work on HEAD.