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| author | Dmitry Vyukov <dvyukov@google.com> | 2017-01-17 14:51:04 +0100 |
|---|---|---|
| committer | Radim Krčmář <rkrcmar@redhat.com> | 2017-01-17 15:06:05 +0100 |
| commit | ce2e852ecc9a42e4b8dabb46025cfef63209234a (patch) | |
| tree | c0a2c20ff888e2a3796bfa08eab9f37eec77633f /arch | |
| parent | 1b1973ef9a6a951903c1d7701f0c420b27e77cf3 (diff) | |
KVM: x86: fix fixing of hypercalls
emulator_fix_hypercall() replaces hypercall with vmcall instruction,
but it does not handle GP exception properly when writes the new instruction.
It can return X86EMUL_PROPAGATE_FAULT without setting exception information.
This leads to incorrect emulation and triggers
WARN_ON(ctxt->exception.vector > 0x1f) in x86_emulate_insn()
as discovered by syzkaller fuzzer:
WARNING: CPU: 2 PID: 18646 at arch/x86/kvm/emulate.c:5558
Call Trace:
warn_slowpath_null+0x2c/0x40 kernel/panic.c:582
x86_emulate_insn+0x16a5/0x4090 arch/x86/kvm/emulate.c:5572
x86_emulate_instruction+0x403/0x1cc0 arch/x86/kvm/x86.c:5618
emulate_instruction arch/x86/include/asm/kvm_host.h:1127 [inline]
handle_exception+0x594/0xfd0 arch/x86/kvm/vmx.c:5762
vmx_handle_exit+0x2b7/0x38b0 arch/x86/kvm/vmx.c:8625
vcpu_enter_guest arch/x86/kvm/x86.c:6888 [inline]
vcpu_run arch/x86/kvm/x86.c:6947 [inline]
Set exception information when write in emulator_fix_hypercall() fails.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: kvm@vger.kernel.org
Cc: syzkaller@googlegroups.com
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 57d8a856cdc5..d153be8929a6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6171,7 +6171,8 @@ static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt) kvm_x86_ops->patch_hypercall(vcpu, instruction); - return emulator_write_emulated(ctxt, rip, instruction, 3, NULL); + return emulator_write_emulated(ctxt, rip, instruction, 3, + &ctxt->exception); } static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu) |