syzbot


KCSAN: data-race in __start_tty / pty_write_room (2)

Status: moderation: reported on 2024/03/27 19:18
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+2af696d31683594c0009@syzkaller.appspotmail.com
First crash: 20d, last: 14d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __start_tty / pty_write_room serial 1 335d 335d 0/26 auto-obsoleted due to no activity on 2023/06/21 16:25

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __start_tty / pty_write_room

write to 0xffff888131fa09bc of 1 bytes by task 18816 on cpu 1:
 __start_tty+0x73/0x170 drivers/tty/tty_io.c:786
 n_tty_ioctl_helper+0x112/0x240 drivers/tty/tty_ioctl.c:963
 n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2511
 tty_ioctl+0x886/0xbe0 drivers/tty/tty_io.c:2812
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:890
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:890
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffff888131fa09bc of 1 bytes by task 1491 on cpu 0:
 pty_write_room+0x1c/0x80 drivers/tty/pty.c:131
 tty_write_room+0x3c/0x60 drivers/tty/tty_ioctl.c:69
 __process_echoes+0x36/0x6b0 drivers/tty/n_tty.c:703
 flush_echoes drivers/tty/n_tty.c:807 [inline]
 __receive_buf drivers/tty/n_tty.c:1632 [inline]
 n_tty_receive_buf_common+0x8e6/0xbd0 drivers/tty/n_tty.c:1729
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1775
 tty_ldisc_receive_buf+0x63/0x100 drivers/tty/tty_buffer.c:387
 tty_port_default_receive_buf+0x59/0x90 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:445 [inline]
 flush_to_ldisc+0x1ce/0x410 drivers/tty/tty_buffer.c:495
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
 worker_thread+0x526/0x730 kernel/workqueue.c:3416
 kthread+0x1d1/0x210 kernel/kthread.c:388
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1491 Comm: kworker/u8:5 Tainted: G        W          6.9.0-rc2-syzkaller-00002-g026e680b0a08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: events_unbound flush_to_ldisc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/02 13:28 upstream 026e680b0a08 eb2966c4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __start_tty / pty_write_room
2024/03/27 19:17 upstream 498e47cd1d1f 120789fd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __start_tty / pty_write_room
* Struck through repros no longer work on HEAD.