On 17/06/2020 11:47, Marc Zyngier wrote:
Hi Steven,
On 2020-06-17 11:43, Steven Price wrote:
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")
Reported-by: James Morse <james.mo...@arm.com>
Signed-off-by: Steven Price <steven.pr...@arm.com>
---
The problematic chunk isn't visible in the diff, so reproduced here:
if (!kvm_arm_vcpu_sve_finalized(vcpu)) {
if (test_bit(KVM_ARM_VCPU_SVE, vcpu->arch.features)) {
ret = kvm_vcpu_enable_sve(vcpu);
if (ret)
goto out;
}
} else {
kvm_vcpu_reset_sve(vcpu);
}
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..f1057603b756 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)) {
Do you really mean this? Seems counter-productive... :-(
Clearly not... I'm really not sure how I managed to screw that up so
badly :(
I'm glad someone is awake!
Sorry about that,
Steve
+ ret = -EINVAL;
goto out;
+ }
pstate = VCPU_RESET_PSTATE_SVC;
} else {
pstate = VCPU_RESET_PSTATE_EL1;
Thanks,
M.
