syzbot


KCSAN: data-race in copy_mm / vm_stat_account

Status: moderation: reported on 2025/11/02 05:47
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+f8b7cc0049cc45632157@syzkaller.appspotmail.com
First crash: 1d06h, last: 1d06h

Sample crash report:
==================================================================
BUG: KCSAN: data-race in copy_mm / vm_stat_account

read-write to 0xffff88811a085200 of 8 bytes by task 6378 on cpu 0:
 vm_stat_account+0xcc/0x110 mm/mmap.c:1358
 mprotect_fixup+0x506/0x570 mm/mprotect.c:849
 do_mprotect_pkey+0x6d6/0x980 mm/mprotect.c:990
 __do_sys_mprotect mm/mprotect.c:1011 [inline]
 __se_sys_mprotect mm/mprotect.c:1008 [inline]
 __x64_sys_mprotect+0x48/0x60 mm/mprotect.c:1008
 x64_sys_call+0x2752/0x3000 arch/x86/include/generated/asm/syscalls_64.h:11
 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

read to 0xffff88811a085080 of 1408 bytes by task 6392 on cpu 1:
 dup_mm kernel/fork.c:1483 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1541
 copy_process+0xd08/0x2000 kernel/fork.c:2181
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2609
 __do_sys_clone kernel/fork.c:2750 [inline]
 __se_sys_clone kernel/fork.c:2734 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2734
 x64_sys_call+0x119c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:57
 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: 6392 Comm: syz.3.646 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/02 05:47 upstream 691d401c7e0e 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_mm / vm_stat_account
* Struck through repros no longer work on HEAD.