On Wed, Jul 12, 2023, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 1c7873e33645 mm: lock newly mapped VMA with corrected orde.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=106f1664a80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=7ad417033279f15a > dashboard link: https://syzkaller.appspot.com/bug?extid=5234e75fb68b86fe89e3 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=146864a8a80000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=134a32bca80000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/7eb52a4d9cf3/disk-1c7873e3.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/b9aa9a9e09e8/vmlinux-1c7873e3.xz > kernel image: https://storage.googleapis.com/syzbot-assets/782d5e4196e2/bzImage-1c7873e3.xz > > The issue was bisected to: > > commit 65966aaca18a5cbf42ac22234cb9cbbf60a4d33c > Author: Sean Christopherson <seanjc@xxxxxxxxxx> > Date: Thu Feb 16 20:22:54 2023 +0000 > > KVM: x86: Assert that the emulator doesn't load CS with garbage in !RM > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16c70f4ca80000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=15c70f4ca80000 > console output: https://syzkaller.appspot.com/x/log.txt?x=11c70f4ca80000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+5234e75fb68b86fe89e3@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 65966aaca18a ("KVM: x86: Assert that the emulator doesn't load CS with garbage in !RM") > > kvm_intel: set kvm_intel.dump_invalid_vmcs=1 to dump internal KVM state. > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 5022 at arch/x86/kvm/emulate.c:1648 __load_segment_descriptor+0xf89/0x1200 arch/x86/kvm/emulate.c:1648 This is the caused by the bug where KVM doesn't check the incoming CR0 provided by userspace via KVM_SET_SREGS, and ultimately ends up with KVM being confused about whether the vCPU is in Real Mode. The new WARN is just the messenger, i.e. detects that KVM is confused. #syz dup: WARNING in kvm_arch_vcpu_ioctl_run (5)
