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KCSAN: data-race in prepare_signal / ptrace_attach (14)

Status: auto-obsoleted due to no activity on 2026/02/06 01:12
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+16fbfb7b2c4b98196060@syzkaller.appspotmail.com
First crash: 192d, last: 192d
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
13289445-d768-45dd-82de-4e1919f28028 assessment-kcsan 💥 KCSAN: data-race in prepare_signal / ptrace_attach (14) 2026/01/10 03:32 2026/01/10 03:32 2026/01/10 03:32 7519916073b761ced56a7b15fdeeb4674e8dc125 
Error 429, Message: You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To moni...
truncated to first 200 bytes; open job for full error
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in prepare_signal / ptrace_attach (5) kernel 6 2 1795d 1809d 0/29 auto-closed as invalid on 2021/08/26 15:59
upstream KCSAN: data-race in prepare_signal / ptrace_attach (12) kernel 6 1 545d 545d 0/29 auto-obsoleted due to no activity on 2025/02/17 10:01
upstream KCSAN: data-race in prepare_signal / ptrace_attach kernel 6 1 2189d 2189d 0/29 auto-closed as invalid on 2020/07/29 00:33
upstream KCSAN: data-race in prepare_signal / ptrace_attach (6) kernel 6 1 1638d 1638d 0/29 auto-closed as invalid on 2022/01/30 21:35
upstream KCSAN: data-race in prepare_signal / ptrace_attach (13) kernel 6 2 412d 431d 0/29 auto-obsoleted due to no activity on 2025/06/30 03:24
upstream KCSAN: data-race in prepare_signal / ptrace_attach (2) kernel 6 3 2112d 2148d 0/29 auto-closed as invalid on 2020/10/13 05:51
upstream KCSAN: data-race in prepare_signal / ptrace_attach (9) kernel 6 1 960d 924d 0/29 auto-obsoleted due to no activity on 2023/12/25 00:07
upstream KCSAN: data-race in prepare_signal / ptrace_attach (11) kernel 6 1 803d 803d 0/29 auto-obsoleted due to no activity on 2024/05/14 10:05
upstream KCSAN: data-race in prepare_signal / ptrace_attach (7) kernel 6 1 1575d 1575d 0/29 auto-closed as invalid on 2022/04/03 14:09
upstream KCSAN: data-race in prepare_signal / ptrace_attach (8) kernel 6 1 1497d 1497d 0/29 auto-closed as invalid on 2022/06/20 14:20
upstream KCSAN: data-race in prepare_signal / ptrace_attach (10) kernel 6 2 849d 874d 0/29 auto-obsoleted due to no activity on 2024/03/29 18:16
upstream KCSAN: data-race in prepare_signal / ptrace_attach (4) kernel 6 1 1879d 1879d 0/29 auto-closed as invalid on 2021/06/03 07:49
upstream KCSAN: data-race in prepare_signal / ptrace_attach (3) kernel 6 2 1973d 2008d 0/29 auto-closed as invalid on 2021/03/01 09:38

Sample crash report:
==================================================================
BUG: KCSAN: data-race in prepare_signal / ptrace_attach

write to 0xffff888104408030 of 4 bytes by task 17687 on cpu 1:
 ptrace_attach+0x26c/0x590 kernel/ptrace.c:462
 __do_sys_ptrace kernel/ptrace.c:1405 [inline]
 __se_sys_ptrace+0x146/0x2c0 kernel/ptrace.c:1387
 __x64_sys_ptrace+0x55/0x70 kernel/ptrace.c:1387
 x64_sys_call+0x2ee5/0x3000 arch/x86/include/generated/asm/syscalls_64.h:102
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104408030 of 4 bytes by task 17693 on cpu 0:
 sig_ignored kernel/signal.c:121 [inline]
 prepare_signal+0x450/0x670 kernel/signal.c:935
 __send_signal_locked+0x30/0x760 kernel/signal.c:1053
 send_signal_locked+0x34e/0x3c0 kernel/signal.c:1216
 do_send_sig_info+0x9f/0xf0 kernel/signal.c:1269
 do_send_specific+0xca/0x110 kernel/signal.c:4131
 do_tkill kernel/signal.c:4152 [inline]
 __do_sys_tgkill kernel/signal.c:4171 [inline]
 __se_sys_tgkill kernel/signal.c:4165 [inline]
 __x64_sys_tgkill+0x127/0x160 kernel/signal.c:4165
 x64_sys_call+0x2d22/0x3000 arch/x86/include/generated/asm/syscalls_64.h:235
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17693 Comm: syz.5.4942 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/12 01:12 upstream d358e5254674 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in prepare_signal / ptrace_attach
* Struck through repros no longer work on HEAD.