From: Steven Price steven.price@arm.com

If SVE is enabled then 'ret' can be assigned the return value of kvm_vcpu_enable_sve() which may be 0 causing future "goto out" sites to erroneously return 0 on failure rather than -EINVAL as expected.

Remove the initialisation of 'ret' and make setting the return value explicit to avoid this situation in the future.

Fixes: 9a3cdf26e336 ("KVM: arm64/sve: Allow userspace to enable SVE for vcpus") Cc: stable@vger.kernel.org Reported-by: James Morse james.morse@arm.com Signed-off-by: Steven Price steven.price@arm.com Signed-off-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/20200617105456.28245-1-steven.price@arm.com --- arch/arm64/kvm/reset.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index d3b209023727..6ed36be51b4b 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -245,7 +245,7 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu) */ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) { - int ret = -EINVAL; + int ret; bool loaded; u32 pstate;

@@ -269,15 +269,19 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)

if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) || test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) { - if (kvm_vcpu_enable_ptrauth(vcpu)) + if (kvm_vcpu_enable_ptrauth(vcpu)) { + ret = -EINVAL; goto out; + } }

switch (vcpu->arch.target) { default: if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) { - if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) + if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) { + ret = -EINVAL; goto out; + } pstate = VCPU_RESET_PSTATE_SVC; } else { pstate = VCPU_RESET_PSTATE_EL1;