When retrieving emulated CPUID entries, check for an insufficient array size if and only if KVM is actually inserting an entry. If userspace has a priori knowledge of the exact array size, KVM_GET_EMULATED_CPUID will incorrectly fail due to effectively requiring an extra, unused entry.
Signed-off-by: Emanuele Giuseppe Esposito eesposit@redhat.com --- arch/x86/kvm/cpuid.c | 33 ++++++++++++++++----------------- 1 file changed, 16 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 6bd2f8b830e4..27059ddf9f0a 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -567,34 +567,33 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func) { - struct kvm_cpuid_entry2 *entry; - - if (array->nent >= array->maxnent) - return -E2BIG; + struct kvm_cpuid_entry2 entry;
- entry = &array->entries[array->nent]; - entry->function = func; - entry->index = 0; - entry->flags = 0; + memset(&entry, 0, sizeof(entry)); + entry.function = func;
switch (func) { case 0: - entry->eax = 7; - ++array->nent; + entry.eax = 7; break; case 1: - entry->ecx = F(MOVBE); - ++array->nent; + entry.ecx = F(MOVBE); break; case 7: - entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; - entry->eax = 0; - entry->ecx = F(RDPID); - ++array->nent; - default: + entry.flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; + entry.eax = 0; + entry.ecx = F(RDPID); break; + default: + goto out; }
+ if (array->nent >= array->maxnent) + return -E2BIG; + + memcpy(&array->entries[array->nent++], &entry, sizeof(entry)); + +out: return 0; }