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[v2,2/4] KVM: selftests: Test vCPU IDs above 2^32

Message ID 20240612215415.3450952-3-minipli@grsecurity.net (mailing list archive)
State New, archived
Headers show
Series KVM: Reject vCPU IDs above 2^32 | expand

Commit Message

Mathias Krause June 12, 2024, 9:54 p.m. UTC 
The KVM_CREATE_VCPU ioctl ABI had an implicit integer truncation bug,
allowing 2^32 aliases for a vCPU ID by setting the upper 32 bits of a 64
bit ioctl() argument.

Verify this no longer works and gets rejected with an error.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
---
 .../selftests/kvm/x86_64/max_vcpuid_cap_test.c        | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
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Patch

diff --git a/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
index 3cc4b86832fe..92cb2f4aef6d 100644
--- a/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
+++ b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
@@ -35,10 +35,19 @@  int main(int argc, char *argv[])
 	TEST_ASSERT(ret < 0,
 		    "Setting KVM_CAP_MAX_VCPU_ID multiple times should fail");
 
-	/* Create vCPU with id beyond KVM_CAP_MAX_VCPU_ID cap*/
+	/* Create vCPU with id beyond KVM_CAP_MAX_VCPU_ID cap */
 	ret = __vm_ioctl(vm, KVM_CREATE_VCPU, (void *)MAX_VCPU_ID);
 	TEST_ASSERT(ret < 0, "Creating vCPU with ID > MAX_VCPU_ID should fail");
 
+	/* Create vCPU with id beyond UINT_MAX */
+	ret = __vm_ioctl(vm, KVM_CREATE_VCPU, (void *)(1L << 32));
+	TEST_ASSERT(ret < 0, "Creating vCPU with ID > UINT_MAX should fail");
+
+	/* Create vCPU with id within bounds */
+	ret = __vm_ioctl(vm, KVM_CREATE_VCPU, (void *)0);
+	TEST_ASSERT(ret >= 0, "Creating vCPU with ID 0 should succeed");
+
+	close(ret);
 	kvm_vm_free(vm);
 	return 0;
 }