From 489cbcf01d1c9e1bf09b7e371d0f312b3a1f3ef2 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 27 Sep 2019 14:45:20 -0700 Subject: KVM: x86: Add WARNs to detect out-of-bounds register indices Add WARN_ON_ONCE() checks in kvm_register_{read,write}() to detect reg values that would cause KVM to overflow vcpu->arch.regs. Change the reg param to an 'int' to make it clear that the reg index is unverified. Regarding the overhead of WARN_ON_ONCE(), now that all fixed GPR reads and writes use dedicated accessors, e.g. kvm_rax_read(), the overhead is limited to flows where the reg index is generated at runtime. And there is at least one historical bug where KVM has generated an out-of- bounds access to arch.regs (see commit b68f3cc7d9789, "KVM: x86: Always use 32-bit SMRAM save state for 32-bit kernels"). Adding the WARN_ON_ONCE() protection paves the way for additional cleanup related to kvm_reg and kvm_reg_ex. Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.h | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'arch/x86/kvm/x86.h') diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index dbf7442a822b..45d82b8277e5 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -238,8 +238,7 @@ static inline bool vcpu_match_mmio_gpa(struct kvm_vcpu *vcpu, gpa_t gpa) return false; } -static inline unsigned long kvm_register_readl(struct kvm_vcpu *vcpu, - enum kvm_reg reg) +static inline unsigned long kvm_register_readl(struct kvm_vcpu *vcpu, int reg) { unsigned long val = kvm_register_read(vcpu, reg); @@ -247,8 +246,7 @@ static inline unsigned long kvm_register_readl(struct kvm_vcpu *vcpu, } static inline void kvm_register_writel(struct kvm_vcpu *vcpu, - enum kvm_reg reg, - unsigned long val) + int reg, unsigned long val) { if (!is_64_bit_mode(vcpu)) val = (u32)val; -- cgit v1.2.3