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KCSAN: data-race in n_tty_receive_buf_common / n_tty_write (6)

Status: moderation: reported on 2024/06/12 16:42
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+78b6cadc25abfcbc3159@syzkaller.appspotmail.com
First crash: 36d, last: 8d19h
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in n_tty_receive_buf_common / n_tty_write (2) serial 36 711d 1049d 0/27 auto-closed as invalid on 2022/09/11 21:39
upstream KCSAN: data-race in n_tty_receive_buf_common / n_tty_write (4) serial 5 470d 561d 0/27 auto-obsoleted due to no activity on 2023/05/10 10:49
upstream KCSAN: data-race in n_tty_receive_buf_common / n_tty_write serial 1 1460d 1460d 0/27 auto-closed as invalid on 2020/08/23 22:27
upstream KCSAN: data-race in n_tty_receive_buf_common / n_tty_write (5) serial 41 80d 223d 0/27 auto-obsoleted due to no activity on 2024/06/03 08:33
upstream KCSAN: data-race in n_tty_receive_buf_common / n_tty_write (3) serial 5 624d 667d 0/27 auto-obsoleted due to no activity on 2022/12/07 10:52

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

write to 0xffffc90000e3b020 of 8 bytes by task 5992 on cpu 1:
 process_echoes drivers/tty/n_tty.c:788 [inline]
 n_tty_write+0x1bc/0xb90 drivers/tty/n_tty.c:2375
 iterate_tty_write drivers/tty/tty_io.c:1021 [inline]
 file_tty_write+0x386/0x690 drivers/tty/tty_io.c:1096
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1117
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x78f/0x900 fs/read_write.c:590
 ksys_write+0xeb/0x1b0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 x64_sys_call+0x27ef/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc90000e3b020 of 8 bytes by task 2074 on cpu 0:
 flush_echoes drivers/tty/n_tty.c:802 [inline]
 __receive_buf drivers/tty/n_tty.c:1642 [inline]
 n_tty_receive_buf_common+0x892/0xbe0 drivers/tty/n_tty.c:1739
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1785
 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:3248 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3329
 worker_thread+0x526/0x720 kernel/workqueue.c:3409
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000000000000 -> 0x0000000000000009

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2074 Comm: kworker/u8:4 Not tainted 6.10.0-rc7-syzkaller-00012-g34afb82a3c67 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: events_unbound flush_to_ldisc
==================================================================
netdevsim netdevsim4 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim4 netdevsim3 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0
netdevsim netdevsim4 netdevsim3 (unregistering): unset [1, 2] type 2 family 0 port 20000 - 0
netdevsim netdevsim4 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim4 netdevsim2 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0
netdevsim netdevsim4 netdevsim2 (unregistering): unset [1, 2] type 2 family 0 port 20000 - 0
team0: Port device netdevsim1 removed
netdevsim netdevsim4 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim4 netdevsim1 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0
netdevsim netdevsim4 netdevsim1 (unregistering): unset [1, 2] type 2 family 0 port 20000 - 0
netdevsim netdevsim4 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim4 netdevsim0 (unregistering): unset [1, 1] type 2 family 0 port 20001 - 0
netdevsim netdevsim4 netdevsim0 (unregistering): unset [1, 2] type 2 family 0 port 20000 - 0
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): Released all slaves
dummy0: left promiscuous mode
batadv0: left promiscuous mode
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Removing interface: team0
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/10 09:36 upstream 34afb82a3c67 bc144f9a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in n_tty_receive_buf_common / n_tty_write
2024/07/06 00:58 upstream d270dd21bee0 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in n_tty_receive_buf_common / n_tty_write
2024/06/21 22:17 upstream 66cc544fd75c edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in n_tty_receive_buf_common / n_tty_write
2024/06/12 16:41 upstream 2ef5971ff345 f815599d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in n_tty_receive_buf_common / n_tty_write
* Struck through repros no longer work on HEAD.