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KCSAN: data-race in install_new_memslots / kvm_read_guest_cached

Status: closed as invalid on 2020/06/18 14:13
Subsystems: kvm
[Documentation on labels]
First crash: 1392d, last: 1392d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in install_new_memslots / kvm_read_guest_cached

write to 0xffff8880b373a000 of 8 bytes by task 20433 on cpu 0:
 install_new_memslots+0xe9/0x130 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1077
 kvm_set_memslot+0x800/0xb70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1153
 __kvm_set_memory_region+0x91c/0xc20 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1300
 kvm_set_memory_region+0x31/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1321
 kvm_vm_ioctl_set_memory_region arch/x86/kvm/../../../virt/kvm/kvm_main.c:1333 [inline]
 kvm_vm_ioctl+0x662/0x18b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3604
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x101/0x150 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x47/0x60 fs/ioctl.c:770
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b373a000 of 8 bytes by task 20438 on cpu 1:
 kvm_read_guest_cached+0x97/0x1f0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2514
 kvm_setup_pvclock_page arch/x86/kvm/x86.c:2356 [inline]
 kvm_guest_time_update arch/x86/kvm/x86.c:2492 [inline]
 vcpu_enter_guest+0x1de0/0x3740 arch/x86/kvm/x86.c:8208
 vcpu_run arch/x86/kvm/x86.c:8544 [inline]
 kvm_arch_vcpu_ioctl_run+0x281/0xd60 arch/x86/kvm/x86.c:8766
 kvm_vcpu_ioctl+0x70b/0x9d0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3138
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x101/0x150 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x47/0x60 fs/ioctl.c:770
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20438 Comm: syz-executor.1 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/06/05 15:23 https://github.com/google/ktsan.git kcsan 7c3cd68e5d38 d36418e9 .config console log report ci2-upstream-kcsan-gce
* Struck through repros no longer work on HEAD.