GH-98897: fix memory leak if math.dist raises exception (GH-98898)

miss-islington · kumaraditya303 · web-flow · commit 078ce6891c2d · 2022-10-31T19:47:29.000-07:00
(cherry picked from commit ab57505) Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
@@ -979,6 +979,11 @@ class T(tuple):
             self.assertEqual(math.dist(p, q), 5*scale)
             self.assertEqual(math.dist(q, p), 5*scale)
 
+    def test_math_dist_leak(self):
+        # gh-98897: Check for error handling does not leak memory
+        with self.assertRaises(ValueError):
+            math.dist([1, 2], [3, 4, 5])
+
     def testIsqrt(self):
         # Test a variety of inputs, large and small.
         test_values = (
diff --git a/Misc/NEWS.d/next/Library/2022-10-31-12-34-03.gh-issue-98897.rgNn4x.rst b/Misc/NEWS.d/next/Library/2022-10-31-12-34-03.gh-issue-98897.rgNn4x.rst
@@ -0,0 +1 @@
+Fix memory leak in :func:`math.dist` when both points don't have the same dimension. Patch by Kumar Aditya.
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
@@ -2658,13 +2658,13 @@ math_dist_impl(PyObject *module, PyObject *p, PyObject *q)
     if (m != n) {
         PyErr_SetString(PyExc_ValueError,
                         "both points must have the same number of dimensions");
-        return NULL;
-
+        goto error_exit;
     }
     if (n > NUM_STACK_ELEMS) {
         diffs = (double *) PyObject_Malloc(n * sizeof(double));
         if (diffs == NULL) {
-            return PyErr_NoMemory();
+            PyErr_NoMemory();
+            goto error_exit;
         }
     }
     for (i=0 ; i<n ; i++) {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Fix memory leak in :func:`math.dist` when both points don't have the same dimension. Patch by Kumar Aditya.
Original file line number	Diff line number	Diff line change
`@@ -2658,13 +2658,13 @@ math_dist_impl(PyObject module, PyObject p, PyObject *q)`
`2658`	`2658`	`if (m != n) {`
`2659`	`2659`	`PyErr_SetString(PyExc_ValueError,`
`2660`	`2660`	`"both points must have the same number of dimensions");`
`2661`		`- return NULL;`
`2662`		`-`
	`2661`	`+ goto error_exit;`
`2663`	`2662`	`}`
`2664`	`2663`	`if (n > NUM_STACK_ELEMS) {`
`2665`	`2664`	`diffs = (double ) PyObject_Malloc(n sizeof(double));`
`2666`	`2665`	`if (diffs == NULL) {`
`2667`		`- return PyErr_NoMemory();`
	`2666`	`+ PyErr_NoMemory();`
	`2667`	`+ goto error_exit;`
`2668`	`2668`	`}`
`2669`	`2669`	`}`
`2670`	`2670`	`for (i=0 ; i<n ; i++) {`