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KCSAN: data-race in do_signal_stop / mm_update_next_owner

Status: auto-closed as invalid on 2020/06/18 14:14
Subsystems: kernel
[Documentation on labels]
First crash: 1510d, last: 1456d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in do_signal_stop / mm_update_next_owner

write to 0xffff888122aaf024 of 4 bytes by task 12911 on cpu 1:
 freezer_do_not_count include/linux/freezer.h:109 [inline]
 freezable_schedule include/linux/freezer.h:171 [inline]
 do_signal_stop+0x1cf/0x4e0 kernel/signal.c:2395
 get_signal+0x601/0x1290 kernel/signal.c:2699
 do_signal+0x2b/0x840 arch/x86/kernel/signal.c:784
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode+0x194/0x1e0 arch/x86/entry/common.c:196
 swapgs_restore_regs_and_return_to_usermode+0x0/0x40

read to 0xffff888122aaf024 of 4 bytes by task 12921 on cpu 0:
 mm_update_next_owner+0x376/0x5a0 kernel/exit.c:383
 exit_mm kernel/exit.c:478 [inline]
 do_exit+0x63c/0x1150 kernel/exit.c:782
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 get_signal+0x2a7/0x1290 kernel/signal.c:2739
 do_signal+0x2b/0x840 arch/x86/kernel/signal.c:784
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12921 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/04/30 19:52 https://github.com/google/ktsan.git kcsan 7c3cd68e5d38 3698959a .config console log report ci2-upstream-kcsan-gce
2020/03/08 05:05 https://github.com/google/ktsan.git kcsan 941e0d917bbf 2e9971bb .config console log report ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.