[PATCH v13 21/85] KVM: Explicitly initialize all fields at the start of kvm_vcpu_map()

Sean Christopherson
2024-10-10T18:49:16Z

Explicitly initialize the entire kvm_host_map structure when mapping a
pfn, as some callers declare their struct on the stack, i.e. don't
zero-initialize the struct, which makes the map->hva in kvm_vcpu_unmap()
*very* suspect.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
virt/kvm/kvm_main.c | 40 ++++++++++++++++------------------------
1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c7691bc40389..f1c9a781315c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3067,32 +3067,24 @@ void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)

int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
{
- kvm_pfn_t pfn;
- void *hva = NULL;
- struct page *page = KVM_UNMAPPED_PAGE;
-
- pfn = gfn_to_pfn(vcpu->kvm, gfn);
- if (is_error_noslot_pfn(pfn))
- return -EINVAL;
-
- if (pfn_valid(pfn)) {
- page = pfn_to_page(pfn);
- hva = kmap(page);
-#ifdef CONFIG_HAS_IOMEM
- } else {
- hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
-#endif
- }
-
- if (!hva)
- return -EFAULT;
-
- map->page = page;
- map->hva = hva;
- map->pfn = pfn;
+ map->page = KVM_UNMAPPED_PAGE;
+ map->hva = NULL;
map->gfn = gfn;

- return 0;
+ map->pfn = gfn_to_pfn(vcpu->kvm, gfn);
+ if (is_error_noslot_pfn(map->pfn))
+ return -EINVAL;
+
+ if (pfn_valid(map->pfn)) {
+ map->page = pfn_to_page(map->pfn);
+ map->hva = kmap(map->page);
+#ifdef CONFIG_HAS_IOMEM
+ } else {
+ map->hva = memremap(pfn_to_hpa(map->pfn), PAGE_SIZE, MEMREMAP_WB);
+#endif
+ }
+
+ return map->hva ? 0 : -EFAULT;
}
EXPORT_SYMBOL_GPL(kvm_vcpu_map);