Issue #20434 Correct error handlin of _PyString_Resize and _PyBytes_Resize

Modules/_io/fileio.c

@@ -549,14 +549,8 @@ fileio_readall(fileio *self)
         }
 
         if (PyBytes_GET_SIZE(result) < (Py_ssize_t)newsize) {
-            if (_PyBytes_Resize(&result, newsize) < 0) {
-                if (total == 0) {
-                    Py_DECREF(result);
-                    return NULL;
-                }
-                PyErr_Clear();
-                break;
-            }
+            if (_PyBytes_Resize(&result, newsize) < 0)
+                return NULL; /* result has been freed */
         }
         Py_BEGIN_ALLOW_THREADS
         errno = 0;
@@ -599,7 +593,6 @@ fileio_readall(fileio *self)
     if (PyBytes_GET_SIZE(result) > total) {
         if (_PyBytes_Resize(&result, total) < 0) {
             /* This should never happen, but just in case */
-            Py_DECREF(result);
             return NULL;
         }
     }
@@ -656,10 +649,8 @@ fileio_read(fileio *self, PyObject *args)
     }
 
     if (n != size) {
-        if (_PyBytes_Resize(&bytes, n) < 0) {
-            Py_DECREF(bytes);
+        if (_PyBytes_Resize(&bytes, n) < 0)
             return NULL;
-        }
     }
 
     return (PyObject *) bytes;

Modules/binascii.c

@@ -320,12 +320,10 @@ binascii_b2a_uu(PyObject *self, PyObject *args)
     }
     *ascii_data++ = '\n';       /* Append a courtesy newline */
 
-    if (_PyString_Resize(&rv,
+    /* rv is cleared on error */
+    (void)_PyString_Resize(&rv,
                        (ascii_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
+                        (unsigned char *)PyString_AS_STRING(rv)));
     PyBuffer_Release(&pbin);
     return rv;
 }
@@ -452,10 +450,8 @@ binascii_a2b_base64(PyObject *self, PyObject *args)
     ** string instead; _PyString_Resize() won't do this for us.
     */
     if (bin_len > 0) {
-        if (_PyString_Resize(&rv, bin_len) < 0) {
-            Py_DECREF(rv);
-            rv = NULL;
-        }
+        /* rv is cleared on error */
+        (void)_PyString_Resize(&rv, bin_len);
     }
     else {
         Py_DECREF(rv);
@@ -522,12 +518,10 @@ binascii_b2a_base64(PyObject *self, PyObject *args)
     }
     *ascii_data++ = '\n';       /* Append a courtesy newline */
 
-    if (_PyString_Resize(&rv,
+    /* rv is cleared on error */
+    (void)_PyString_Resize(&rv,
                        (ascii_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
+                        (unsigned char *)PyString_AS_STRING(rv)));
     PyBuffer_Release(&pbuf);
     return rv;
 }
@@ -601,13 +595,10 @@ binascii_a2b_hqx(PyObject *self, PyObject *args)
         Py_DECREF(rv);
         return NULL;
     }
+    /* rv is cleared on error */
     if (_PyString_Resize(&rv,
                        (bin_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
-    if (rv) {
+                        (unsigned char *)PyString_AS_STRING(rv))) == 0) {
         PyObject *rrv = Py_BuildValue("Oi", rv, done);
         PyBuffer_Release(&pascii);
         Py_DECREF(rv);
@@ -672,12 +663,10 @@ binascii_rlecode_hqx(PyObject *self, PyObject *args)
             }
         }
     }
-    if (_PyString_Resize(&rv,
+    /* rv is cleared on error */
+    (void)_PyString_Resize(&rv,
                        (out_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
+                        (unsigned char *)PyString_AS_STRING(rv)));
     PyBuffer_Release(&pbuf);
     return rv;
 }
@@ -729,12 +718,10 @@ binascii_b2a_hqx(PyObject *self, PyObject *args)
         leftchar <<= (6-leftbits);
         *ascii_data++ = table_b2a_hqx[leftchar & 0x3f];
     }
-    if (_PyString_Resize(&rv,
+    /* rv is cleared on error */
+    (void)_PyString_Resize(&rv,
                        (ascii_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
+                        (unsigned char *)PyString_AS_STRING(rv)));
     PyBuffer_Release(&pbin);
     return rv;
 }
@@ -796,7 +783,7 @@ binascii_rledecode_hqx(PyObject *self, PyObject *args)
              if ( --out_len_left < 0 ) { \
                       if ( out_len > PY_SSIZE_T_MAX / 2) return PyErr_NoMemory(); \
                       if (_PyString_Resize(&rv, 2*out_len) < 0) \
-                        { Py_DECREF(rv); PyBuffer_Release(&pin); return NULL; } \
+                        { PyBuffer_Release(&pin); return NULL; } \
                       out_data = (unsigned char *)PyString_AS_STRING(rv) \
                                                              + out_len; \
                       out_len_left = out_len-1; \
@@ -846,12 +833,10 @@ binascii_rledecode_hqx(PyObject *self, PyObject *args)
             OUTBYTE(in_byte);
         }
     }
-    if (_PyString_Resize(&rv,
+    /* rv is cleared on error */
+    (void)_PyString_Resize(&rv,
                        (out_data -
-                        (unsigned char *)PyString_AS_STRING(rv))) < 0) {
-        Py_DECREF(rv);
-        rv = NULL;
-    }
+                        (unsigned char *)PyString_AS_STRING(rv)));
     PyBuffer_Release(&pin);
     return rv;
 }

Modules/bz2module.c

@@ -732,7 +732,8 @@ BZ2File_readlines(BZ2FileObject *self, PyObject *args)
             }
             else {
                 /* Grow the big buffer */
-                _PyString_Resize(&big_buffer, buffersize);
+                if (_PyString_Resize(&big_buffer, buffersize))
+                    goto error;
                 buffer = PyString_AS_STRING(big_buffer);
             }
             continue;

Objects/bytearrayobject.c

@@ -994,10 +994,8 @@ bytearray_repr(PyByteArrayObject *self)
            *p++ = *quote_postfix++;
         }
         *p = '\0';
-        if (_PyString_Resize(&v, (p - PyString_AS_STRING(v)))) {
-            Py_DECREF(v);
-            return NULL;
-        }
+        /* v is cleared on error */
+        (void)_PyString_Resize(&v, (p - PyString_AS_STRING(v)));
         return v;
     }
 }

Objects/stringobject.c

@@ -748,8 +748,8 @@ PyObject *PyString_DecodeEscape(const char *s,
                              UTF-8 bytes may follow. */
         }
     }
-    if (p-buf < newlen && _PyString_Resize(&v, p - buf))
-        goto failed;
+    if (p-buf < newlen)
+        _PyString_Resize(&v, p - buf); /* v is cleared on error */
     return v;
   failed:
     Py_DECREF(v);

PC/_subprocess.c

@@ -367,7 +367,8 @@ getenvironment(PyObject* environment)
                                                      vsize + 1 + 1;
         if (totalsize > PyString_GET_SIZE(out)) {
             int offset = p - PyString_AS_STRING(out);
-            _PyString_Resize(&out, totalsize + 1024);
+            if (_PyString_Resize(&out, totalsize + 1024))
+                goto exit;
             p = PyString_AS_STRING(out) + offset;
         }
         memcpy(p, PyString_AS_STRING(key), ksize);
@@ -383,7 +384,7 @@ getenvironment(PyObject* environment)
     _PyString_Resize(&out, p - PyString_AS_STRING(out));
 
     /* PyObject_Print(out, stdout, 0); */
-
+exit:
     Py_XDECREF(keys);
     Py_XDECREF(values);