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KVM: x86: Harden copying of userspace-array against overflow

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cpuid.c utilizes vmemdup_user() and array_size() to copy two userspace
arrays. This, currently, does not check for an overflow.

Use the new wrapper vmemdup_array_user() to copy the arrays more safely,
as vmemdup_user() doesn't check for overflow.

Note, KVM explicitly checks the number of entries before duplicating the
array, i.e. adding the overflow check should be a glorified nop.

Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Link: https://lore.kernel.org/r/20231102181526.43279-2-pstanner@redhat.com
[sean: call out that KVM pre-checks the number of entries]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Philipp Stanner 2023-11-02 19:15:24 +01:00 committed by Sean Christopherson
parent 63912245c1
commit 573cc0e5cf
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/cpuid.c
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@ -469,7 +469,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
return -E2BIG;
if (cpuid->nent) {
e = vmemdup_user(entries, array_size(sizeof(*e), cpuid->nent));
e = vmemdup_array_user(entries, cpuid->nent, sizeof(*e));
if (IS_ERR(e))
return PTR_ERR(e);
@ -513,7 +513,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
return -E2BIG;
if (cpuid->nent) {
e2 = vmemdup_user(entries, array_size(sizeof(*e2), cpuid->nent));
e2 = vmemdup_array_user(entries, cpuid->nent, sizeof(*e2));
if (IS_ERR(e2))
return PTR_ERR(e2);
}