Added a dimension check in MatMulComputeHelper to ensure the inner dimension K_

onnxruntime/core/providers/cpu/math/matmul_helper.h

@@ -168,6 +168,9 @@ class MatMulComputeHelper {
       if (num_output_dims == 0) {
         // for left and right being both vector, output is scalar thus no shape
         ORT_RETURN_IF_NOT(M_ == 1 && N_ == 1, "M_ == 1 && N_ == 1 was false");
+        ORT_RETURN_IF_NOT(K_ == right_shape[0],
+                          "MatMul dimension mismatch. Left vector K (",
+                          K_, ") != right vector K (", right_shape[0], ")");
       } else {
         if (left_num_dims == 1) {
           ORT_RETURN_IF_NOT(num_dims_with_pad - 1 == num_output_dims, "num_dims_with_pad - 1 != num_output_dims");

onnxruntime/test/providers/cpu/math/matmul_integer_test.cc

@@ -504,5 +504,55 @@ TEST(MatmulIntegerOpTest, SharedPrepackedWeights) {
 }
 #endif
 
+// Regression test: 1D vector dot product with matching K dimension should succeed.
+// A=[K], B=[K] -> scalar output (dot product).
+TEST(MatmulIntegerOpTest, MatMulInteger_1D_Vector_DotProduct) {
+  OpTester test("MatMulInteger", 10);
+  test.AddInput<uint8_t>("T1", {4}, {1, 2, 3, 4});
+  test.AddInput<uint8_t>("T2", {4}, {5, 6, 7, 8});
+  test.AddInput<uint8_t>("a_zero_point", {}, {0});
+  test.AddInput<uint8_t>("b_zero_point", {}, {0});
+  // dot product: 1*5 + 2*6 + 3*7 + 4*8 = 5 + 12 + 21 + 32 = 70
+  test.AddOutput<int32_t>("T3", {}, {70});
+  test.Run(OpTester::ExpectResult::kExpectSuccess, "", {kDmlExecutionProvider});
+}
+
+// Same 1D vector dot product test with int8_t types.
+TEST(MatmulIntegerOpTest, MatMulInteger_1D_Vector_DotProduct_int8) {
+  OpTester test("MatMulInteger", 10);
+  test.AddInput<int8_t>("T1", {3}, {1, -2, 3});
+  test.AddInput<int8_t>("T2", {3}, {4, 5, -6});
+  test.AddInput<int8_t>("a_zero_point", {}, {0});
+  test.AddInput<int8_t>("b_zero_point", {}, {0});
+  // dot product: 1*4 + (-2)*5 + 3*(-6) = 4 - 10 - 18 = -24
+  test.AddOutput<int32_t>("T3", {}, {-24});
+  test.Run(OpTester::ExpectResult::kExpectSuccess, "", {kDmlExecutionProvider});
+}
+
+// Regression test: 1D vectors with mismatched K dimension must fail safely.
+// Covers prior invalid-shape handling for A=[K], B=[1] where K > 1.
+TEST(MatmulIntegerOpTest, MatMulInteger_1D_Vector_KDimensionMismatch) {
+  OpTester test("MatMulInteger", 10);
+  test.AddShapeToTensorData(false);
+  test.AddInput<uint8_t>("T1", {4}, {1, 1, 1, 1});
+  test.AddInput<uint8_t>("T2", {1}, {5});
+  test.AddInput<uint8_t>("a_zero_point", {}, {0});
+  test.AddInput<uint8_t>("b_zero_point", {}, {0});
+  test.AddOutput<int32_t>("T3", {}, {0});
+  test.Run(OpTester::ExpectResult::kExpectFailure, "MatMul dimension mismatch");
+}
+
+// Same regression test with int8_t types.
+TEST(MatmulIntegerOpTest, MatMulInteger_int8_1D_Vector_KDimensionMismatch) {
+  OpTester test("MatMulInteger", 10);
+  test.AddShapeToTensorData(false);
+  test.AddInput<int8_t>("T1", {8}, {1, 1, 1, 1, 1, 1, 1, 1});
+  test.AddInput<int8_t>("T2", {1}, {5});
+  test.AddInput<int8_t>("a_zero_point", {}, {0});
+  test.AddInput<int8_t>("b_zero_point", {}, {0});
+  test.AddOutput<int32_t>("T3", {}, {0});
+  test.Run(OpTester::ExpectResult::kExpectFailure, "MatMul dimension mismatch");
+}
+
 }  // namespace test
 }  // namespace onnxruntime