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| author |   Maxim Levitsky <mlevitsk@redhat.com> | 2020-08-27 20:11:44 +0300 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2020-09-12 12:22:55 -0400 |
| commit | 37f66bbef0920429b8cb5eddba849ec4308a9f8e (patch) | |
| tree | 67f132e53a670820276243ba7238aba555ae8484 /arch | |
| parent | KVM: nSVM: more strict SMM checks when returning to nested guest (diff) | |
| download | wireguard-linux-37f66bbef0920429b8cb5eddba849ec4308a9f8e.tar.xz wireguard-linux-37f66bbef0920429b8cb5eddba849ec4308a9f8e.zip | |
KVM: emulator: more strict rsm checks.
Don't ignore return values in rsm_load_state_64/32 to avoid
loading invalid state from SMM state area if it was tampered with
by the guest.
This is primarly intended to avoid letting guest set bits in EFER
(like EFER.SVME when nesting is disabled) by manipulating SMM save area.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827171145.374620-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index d0e2825ae617..1d450d7710d6 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2505,9 +2505,14 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt, *reg_write(ctxt, i) = GET_SMSTATE(u32, smstate, 0x7fd0 + i * 4); val = GET_SMSTATE(u32, smstate, 0x7fcc); - ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1); + + if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1)) + return X86EMUL_UNHANDLEABLE; + val = GET_SMSTATE(u32, smstate, 0x7fc8); - ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1); + + if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1)) + return X86EMUL_UNHANDLEABLE; selector = GET_SMSTATE(u32, smstate, 0x7fc4); set_desc_base(&desc, GET_SMSTATE(u32, smstate, 0x7f64)); @@ -2560,16 +2565,23 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7f70) | X86_EFLAGS_FIXED; val = GET_SMSTATE(u32, smstate, 0x7f68); - ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1); + + if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1)) + return X86EMUL_UNHANDLEABLE; + val = GET_SMSTATE(u32, smstate, 0x7f60); - ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1); + + if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1)) + return X86EMUL_UNHANDLEABLE; cr0 = GET_SMSTATE(u64, smstate, 0x7f58); cr3 = GET_SMSTATE(u64, smstate, 0x7f50); cr4 = GET_SMSTATE(u64, smstate, 0x7f48); ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smstate, 0x7f00)); val = GET_SMSTATE(u64, smstate, 0x7ed0); - ctxt->ops->set_msr(ctxt, MSR_EFER, val & ~EFER_LMA); + + if (ctxt->ops->set_msr(ctxt, MSR_EFER, val & ~EFER_LMA)) + return X86EMUL_UNHANDLEABLE; selector = GET_SMSTATE(u32, smstate, 0x7e90); rsm_set_desc_flags(&desc, GET_SMSTATE(u32, smstate, 0x7e92) << 8); |