syzbot


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

Status: auto-obsoleted due to no activity on 2024/04/15 08:15
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+fcde7e76b867d89edc2d@syzkaller.appspotmail.com
First crash: 41d, last: 41d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __start_tty / n_tty_receive_char serial 1 339d 339d 0/26 auto-obsoleted due to no activity on 2023/06/22 00:17
upstream KCSAN: data-race in __start_tty / n_tty_receive_char (3) serial 2 21h57m 1d22h 0/26 moderation: reported on 2024/04/19 10:17

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

write to 0xffff88813ffb55bc of 1 bytes by task 22167 on cpu 1:
 __start_tty+0x73/0x160 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+0x875/0xbc0 drivers/tty/tty_io.c:2812
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813ffb55bc of 1 bytes by task 19364 on cpu 0:
 n_tty_receive_char+0x3d/0x670 drivers/tty/n_tty.c:1427
 n_tty_receive_buf_standard+0x4bd/0x2e20 drivers/tty/n_tty.c:1606
 __receive_buf drivers/tty/n_tty.c:1630 [inline]
 n_tty_receive_buf_common+0x7e5/0xbc0 drivers/tty/n_tty.c:1729
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1775
 tty_ldisc_receive_buf+0x60/0xe0 drivers/tty/tty_buffer.c:386
 tty_port_default_receive_buf+0x59/0x90 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:444 [inline]
 flush_to_ldisc+0x1ca/0x400 drivers/tty/tty_buffer.c:494
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x5b8/0xa40 kernel/workqueue.c:2706
 worker_thread+0x525/0x730 kernel/workqueue.c:2787
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:243

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19364 Comm: kworker/u4:86 Not tainted 6.8.0-rc7-syzkaller-00260-gfa4b851b4ad6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Workqueue: events_unbound flush_to_ldisc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/11 08:14 upstream fa4b851b4ad6 6ee49f2e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __start_tty / n_tty_receive_char
* Struck through repros no longer work on HEAD.