syzbot


KCSAN: data-race in memcpy_and_pad / set_task_ioprio

Status: moderation: reported on 2026/03/22 03:03
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+2e3fa5e1374ebec8a9ad@syzkaller.appspotmail.com
First crash: 6d05h, last: 6d05h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
9767006d-c3ba-46b4-a114-8dd8d8e1463e assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in memcpy_and_pad / set_task_ioprio 2026/03/22 03:02 2026/03/22 03:02 2026/03/22 03:05 f84caa2f84dea47b51a188e8d6267f295e89bbcb

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

write to 0xffff88810d0e88f8 of 8 bytes by task 7165 on cpu 0:
 set_task_ioprio+0x24e/0x270 block/blk-ioc.c:280
 __do_sys_ioprio_set block/ioprio.c:121 [inline]
 __se_sys_ioprio_set+0x24f/0x5a0 block/ioprio.c:65
 __x64_sys_ioprio_set+0x43/0x50 block/ioprio.c:65
 x64_sys_call+0x2bbf/0x3020 arch/x86/include/generated/asm/syscalls_64.h:252
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810d0e8000 of 3328 bytes by task 7161 on cpu 1:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1008
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:108
 dup_task_struct+0x6e/0x950 kernel/fork.c:920
 copy_process+0x37e/0x20b0 kernel/fork.c:2050
 kernel_clone+0x16b/0x5d0 kernel/fork.c:2653
 __do_sys_clone3 kernel/fork.c:2955 [inline]
 __se_sys_clone3+0x1f5/0x230 kernel/fork.c:2934
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:2934
 x64_sys_call+0x580/0x3020 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 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: 7161 Comm: syz.0.8700 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/22 03:02 upstream a0c83177734a 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in memcpy_and_pad / set_task_ioprio
* Struck through repros no longer work on HEAD.