syzbot


KCSAN: data-race in __se_sys_mremap / vma_complete

Status: moderation: reported on 2025/12/29 03:01
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+f76e73cc28fed0483dba@syzkaller.appspotmail.com
First crash: 8d05h, last: 8d05h

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __se_sys_mremap / vma_complete

read-write to 0xffff88810de45948 of 4 bytes by task 9936 on cpu 1:
 vma_complete+0x13f/0x580 mm/vma.c:349
 __split_vma+0x59b/0x660 mm/vma.c:561
 split_vma mm/vma.c:591 [inline]
 vma_modify+0xb53/0xd50 mm/vma.c:1626
 vma_modify_flags+0x10c/0x190 mm/vma.c:1654
 mprotect_fixup+0x30f/0x5e0 mm/mprotect.c:756
 do_mprotect_pkey+0x6d6/0x980 mm/mprotect.c:930
 __do_sys_mprotect mm/mprotect.c:951 [inline]
 __se_sys_mprotect mm/mprotect.c:948 [inline]
 __x64_sys_mprotect+0x48/0x60 mm/mprotect.c:948
 x64_sys_call+0x2c3b/0x3000 arch/x86/include/generated/asm/syscalls_64.h:11
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810de45948 of 4 bytes by task 9942 on cpu 0:
 check_mremap_params mm/mremap.c:1820 [inline]
 do_mremap mm/mremap.c:1924 [inline]
 __do_sys_mremap mm/mremap.c:1997 [inline]
 __se_sys_mremap+0x420/0xb30 mm/mremap.c:1965
 __x64_sys_mremap+0x67/0x80 mm/mremap.c:1965
 x64_sys_call+0x2944/0x3000 arch/x86/include/generated/asm/syscalls_64.h:26
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000023 -> 0x00000025

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9942 Comm: syz.1.2193 Not tainted syzkaller #0 PREEMPT(voluntary) 
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
2025/12/29 03:01 upstream c875a6c32467 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __se_sys_mremap / vma_complete
* Struck through repros no longer work on HEAD.