On Mon, Nov 06, 2017 at 12:51:57PM +0100, David Hildenbrand wrote: > On 31.10.2017 12:34, syzbot wrote: > > Hello, > > > > syzkaller hit the following crash on > > 91dfed74eabcdae9378131546c446442c29bf769 > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master > > compiler: gcc (GCC) 7.1.1 20170620 > > .config is attached > > Raw console output is attached. > > C reproducer is attached > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > > for information about syzkaller reproducers > > > > > > in_atomic(): 1, irqs_disabled(): 0, pid: 2909, name: syzkaller879109 > > 2 locks held by syzkaller879109/2909: > > #0: (&vcpu->mutex){+.+.}, at: [<ffffffff8106222c>] vcpu_load+0x1c/0x70 > > arch/x86/kvm/../../../virt/kvm/kvm_main.c:154 > > #1: (&kvm->srcu){....}, at: [<ffffffff810dd162>] vcpu_enter_guest > > arch/x86/kvm/x86.c:6983 [inline] > > #1: (&kvm->srcu){....}, at: [<ffffffff810dd162>] vcpu_run > > arch/x86/kvm/x86.c:7061 [inline] > > #1: (&kvm->srcu){....}, at: [<ffffffff810dd162>] > > kvm_arch_vcpu_ioctl_run+0x1bc2/0x58b0 arch/x86/kvm/x86.c:7222 > > CPU: 1 PID: 2909 Comm: syzkaller879109 Not tainted 4.13.0-rc4-next-20170811 > > #1 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:16 [inline] > > dump_stack+0x194/0x257 lib/dump_stack.c:52 > > ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6014 > > __might_sleep+0x95/0x190 kernel/sched/core.c:5967 > > __might_fault+0xab/0x1d0 mm/memory.c:4383 > > __copy_from_user include/linux/uaccess.h:71 [inline] > > __kvm_read_guest_page+0x58/0xa0 > > arch/x86/kvm/../../../virt/kvm/kvm_main.c:1771 > > kvm_vcpu_read_guest_page+0x44/0x60 > > arch/x86/kvm/../../../virt/kvm/kvm_main.c:1791 > > kvm_read_guest_virt_helper+0x76/0x140 arch/x86/kvm/x86.c:4407 > > kvm_read_guest_virt_system+0x3c/0x50 arch/x86/kvm/x86.c:4466 > > segmented_read_std+0x10c/0x180 arch/x86/kvm/emulate.c:819 > > em_fxrstor+0x27b/0x410 arch/x86/kvm/emulate.c:4022 > > > In em_fxrstor, we do a get_fpu(), which in return disables preemption. > > With preempt_disable(), we do a > segmented_read_std()->kvm_vcpu_read_guest_page(), triggering the warning. > > > x86_emulate_insn+0x55d/0x3c50 arch/x86/kvm/emulate.c:5471 > > x86_emulate_instruction+0x411/0x1ca0 arch/x86/kvm/x86.c:5698 > > kvm_mmu_page_fault+0x18b/0x2c0 arch/x86/kvm/mmu.c:4854 > > handle_ept_violation+0x1fc/0x5e0 arch/x86/kvm/vmx.c:6400 > > vmx_handle_exit+0x281/0x1ab0 arch/x86/kvm/vmx.c:8718 > > vcpu_enter_guest arch/x86/kvm/x86.c:6999 [inline] > > vcpu_run arch/x86/kvm/x86.c:7061 [inline] > > kvm_arch_vcpu_ioctl_run+0x1cee/0x58b0 arch/x86/kvm/x86.c:7222 > > kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2591 > > vfs_ioctl fs/ioctl.c:45 [inline] > > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 > > SYSC_ioctl fs/ioctl.c:700 [inline] > > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 > > entry_SYSCALL_64_fastpath+0x1f/0xbe > This is fixed now (thanks David!), so closing the bug: #syz fix: KVM: x86: fix em_fxstor() sleeping while in atomic However, isn't this also needed in 4.14-stable?
