syzbot


KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step

Status: moderation: reported on 2025/05/27 08:18
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+21167ad055e79662a0ba@syzkaller.appspotmail.com
First crash: 51d, last: 3d04h

Sample crash report:
==================================================================
BUG: KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step

write to 0xffff88811990949c of 4 bytes by task 28 on cpu 0:
 rcu_tasks_trace_pertask_prep kernel/rcu/tasks.h:1784 [inline]
 rcu_tasks_trace_pregp_step+0x1ac/0x920 kernel/rcu/tasks.h:1828
 rcu_tasks_wait_gp+0x88/0x530 kernel/rcu/tasks.h:826
 rcu_tasks_one_gp+0x7f6/0x8e0 kernel/rcu/tasks.h:622
 rcu_tasks_kthread+0xf7/0x110 kernel/rcu/tasks.h:658
 kthread+0x489/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888119909040 of 3200 bytes by task 4545 on cpu 1:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1007
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:98
 dup_task_struct+0x83/0x6a0 kernel/fork.c:873
 copy_process+0x399/0x1f90 kernel/fork.c:1999
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2599
 __do_sys_clone3 kernel/fork.c:2903 [inline]
 __se_sys_clone3+0x1c2/0x200 kernel/fork.c:2882
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:2882
 x64_sys_call+0x10c9/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4545 Comm: syz.2.263 Not tainted 6.16.0-rc6-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/14 22:07 upstream 347e9f5043c8 d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/12 15:12 upstream 379f604cc3dc 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/09 14:09 upstream 733923397fd9 f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/07 04:46 upstream d7b8f8e20813 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/05 13:15 upstream a79a588fc176 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/04 18:37 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/07/04 01:27 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/06/21 00:28 upstream 75f5f23f8787 804b3919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/06/09 21:15 upstream 19272b37aa4f 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/06/08 12:13 upstream 8630c59e9936 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/06/02 07:53 upstream cd2e103d57e5 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/06/01 16:24 upstream 4cb6c8af8591 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/05/28 07:00 upstream dd3922cf9d4d 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
2025/05/27 08:18 upstream 785cdec46e92 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step
* Struck through repros no longer work on HEAD.