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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: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2011-05-07 16:35:38 +09:00 committed by Avi Kivity
parent 12cb814f3b
commit fa3d315a4c
2 changed files with 6 additions and 3 deletions
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2
arch/x86/kvm/paging_tmpl.h
View File

@ -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;
}

7
virt/kvm/kvm_main.c
View File

@ -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;