Commit fa3d315a authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
Browse files

KVM: Validate userspace_addr of memslot when registered 



This way, we can avoid checking the user space address many times when
we read the guest memory.

Although we can do the same for write if we check which slots are
writable, we do not care write now: reading the guest memory happens
more often than writing.

[avi: change VERIFY_READ to VERIFY_WRITE]

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 12cb814f

arch/x86/kvm/paging_tmpl.h

+1 −1
Original line number Diff line number Diff line
@@ -185,7 +185,7 @@ walk: 
		}



		ptep_user = (pt_element_t __user *)((void *)host_addr + offset);

		if (unlikely(copy_from_user(&pte, ptep_user, sizeof(pte)))) {

		if (unlikely(__copy_from_user(&pte, ptep_user, sizeof(pte)))) {

			present = false;

			break;

		}

virt/kvm/kvm_main.c

+5 −2
Original line number Diff line number Diff line
@@ -648,7 +648,10 @@ int __kvm_set_memory_region(struct kvm *kvm, 
		goto out;

	if (mem->guest_phys_addr & (PAGE_SIZE - 1))

		goto out;

	if (user_alloc && (mem->userspace_addr & (PAGE_SIZE - 1)))

	/* We can read the guest memory with __xxx_user() later on. */

	if (user_alloc &&

	    ((mem->userspace_addr & (PAGE_SIZE - 1)) ||

	     !access_ok(VERIFY_WRITE, mem->userspace_addr, mem->memory_size)))

		goto out;

	if (mem->slot >= KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)

		goto out;
@@ -1283,7 +1286,7 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, 
	addr = gfn_to_hva(kvm, gfn);

	if (kvm_is_error_hva(addr))

		return -EFAULT;

	r = copy_from_user(data, (void __user *)addr + offset, len);

	r = __copy_from_user(data, (void __user *)addr + offset, len);

	if (r)

		return -EFAULT;

	return 0;

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