Issue #24456: Fixed possible buffer over-read in adpcm2lin() and lin2adpcm()

functions of the audioop module.

1 files changed, 26 insertions, 13 deletions

diff --git a/Modules/audioop.c b/Modules/audioop.c
index 0358147f92..5efed0c661 100644
--- a/Modules/audioop.c
+++ b/Modules/audioop.c
@@ -1615,23 +1615,30 @@ audioop_lin2adpcm_impl(PyModuleDef *module, Py_buffer *fragment, int width, PyOb
     if (!audioop_check_parameters(fragment->len, width))
         return NULL;
 
-    str = PyBytes_FromStringAndSize(NULL, fragment->len/(width*2));
-    if (str == NULL)
-        return NULL;
-    ncp = (signed char *)PyBytes_AsString(str);
-
     /* Decode state, should have (value, step) */
     if ( state == Py_None ) {
         /* First time, it seems. Set defaults */
         valpred = 0;
         index = 0;
-    } else if (!PyTuple_Check(state)) {
+    }
+    else if (!PyTuple_Check(state)) {
         PyErr_SetString(PyExc_TypeError, "state must be a tuple or None");
-        goto exit;
-    } else if (!PyArg_ParseTuple(state, "ii", &valpred, &index)) {
-        goto exit;
+        return NULL;
+    }
+    else if (!PyArg_ParseTuple(state, "ii", &valpred, &index)) {
+        return NULL;
+    }
+    else if (valpred >= 0x8000 || valpred < -0x8000 ||
+             (size_t)index >= Py_ARRAY_LENGTH(stepsizeTable)) {
+        PyErr_SetString(PyExc_ValueError, "bad state");
+        return NULL;
     }
 
+    str = PyBytes_FromStringAndSize(NULL, fragment->len/(width*2));
+    if (str == NULL)
+        return NULL;
+    ncp = (signed char *)PyBytes_AsString(str);
+
     step = stepsizeTable[index];
     bufferstep = 1;
 
@@ -1706,8 +1713,6 @@ audioop_lin2adpcm_impl(PyModuleDef *module, Py_buffer *fragment, int width, PyOb
         bufferstep = !bufferstep;
     }
     rv = Py_BuildValue("(O(ii))", str, valpred, index);
-
-  exit:
     Py_DECREF(str);
     return rv;
 }
@@ -1742,11 +1747,19 @@ audioop_adpcm2lin_impl(PyModuleDef *module, Py_buffer *fragment, int width, PyOb
         /* First time, it seems. Set defaults */
         valpred = 0;
         index = 0;
-    } else if (!PyTuple_Check(state)) {
+    }
+    else if (!PyTuple_Check(state)) {
         PyErr_SetString(PyExc_TypeError, "state must be a tuple or None");
         return NULL;
-    } else if (!PyArg_ParseTuple(state, "ii", &valpred, &index))
+    }
+    else if (!PyArg_ParseTuple(state, "ii", &valpred, &index)) {
+        return NULL;
+    }
+    else if (valpred >= 0x8000 || valpred < -0x8000 ||
+             (size_t)index >= Py_ARRAY_LENGTH(stepsizeTable)) {
+        PyErr_SetString(PyExc_ValueError, "bad state");
         return NULL;
+    }
 
     if (fragment->len > (PY_SSIZE_T_MAX/2)/width) {
         PyErr_SetString(PyExc_MemoryError,