On Mon, Jun 12, 2023, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 64569520920a Merge tag 'block-6.4-2023-06-09' of git://git.. > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=12386cd9280000 > kernel config: https://syzkaller.appspot.com/x/.config?x=3c980bfe8b399968 > dashboard link: https://syzkaller.appspot.com/bug?extid=5feef0b9ee9c8e9e5689 > 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=13adcb43280000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13af3853280000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/4421ae3b4ee0/disk-64569520.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/9312cbb35f54/vmlinux-64569520.xz > kernel image: https://storage.googleapis.com/syzbot-assets/3476854febf3/bzImage-64569520.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+5feef0b9ee9c8e9e5689@xxxxxxxxxxxxxxxxxxxxxxxxx > > kvm_intel: L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details. > kvm: vcpu 1: requested 128 ns lapic timer period limited to 200000 ns > kvm: vcpu 1: requested lapic timer restore with starting count register 0x390=1812281087 (231971979136 ns) > initial count (200000 ns). Using initial count to start timer. > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 5004 at arch/x86/kvm/x86.c:11099 kvm_arch_vcpu_ioctl_run+0x2379/0x2820 arch/x86/kvm/x86.c:11099 > Modules linked in: > CPU: 1 PID: 5004 Comm: syz-executor120 Not tainted 6.4.0-rc5-syzkaller-00245-g64569520920a #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023 > RIP: 0010:kvm_arch_vcpu_ioctl_run+0x2379/0x2820 arch/x86/kvm/x86.c:11099 KVM doesn't reject KVM_SET_SREGS with a bad CR0, which combined with an L2 that's configured with unrestricted guest *disabled*, coerces KVM into stuffing VM86 state to virtualize Real Mode, and eventually leads to all kinds of weirdness. Will post a patch "shortly" (probably tomorrow at this point).
