From: Maxim Levitsky Date: Thu, 27 Aug 2020 17:11:44 +0000 (+0300) Subject: KVM: emulator: more strict rsm checks. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=37f66bbef0920429b8cb5eddba849ec4308a9f8e;p=linux.git 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 Message-Id: <20200827171145.374620-8-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index d0e2825ae6174..1d450d7710d63 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);