@@ -181,12 +181,9 @@ PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t);
 #endif
 
 #define _PyObject_VAR_SIZE(typeobj, nitems)     \
-    (size_t)                                    \
-    ( ( (typeobj)->tp_basicsize +               \
-        (nitems)*(typeobj)->tp_itemsize +       \
-        (SIZEOF_VOID_P - 1)                     \
-      ) & ~(SIZEOF_VOID_P - 1)                  \
-    )
+    _Py_SIZE_ROUND_UP((typeobj)->tp_basicsize + \
+        (nitems)*(typeobj)->tp_itemsize,        \
+        SIZEOF_VOID_P)
 
 #define PyObject_NEW(type, typeobj) \
 ( (type *) PyObject_Init( \
 
@@ -52,4 +52,18 @@
 #define PyDoc_STR(str) ""
 #endif
 
+/* Below "a" is a power of 2. */
+/* Round down size "n" to be a multiple of "a". */
+#define _Py_SIZE_ROUND_DOWN(n, a) ((size_t)(n) & ~(size_t)((a) - 1))
+/* Round up size "n" to be a multiple of "a". */
+#define _Py_SIZE_ROUND_UP(n, a) (((size_t)(n) + \
+        (size_t)((a) - 1)) & ~(size_t)((a) - 1))
+/* Round pointer "p" down to the closest "a"-aligned address <= "p". */
+#define _Py_ALIGN_DOWN(p, a) ((void *)((Py_uintptr_t)(p) & ~(Py_uintptr_t)((a) - 1)))
+/* Round pointer "p" up to the closest "a"-aligned address >= "p". */
+#define _Py_ALIGN_UP(p, a) ((void *)(((Py_uintptr_t)(p) + \
+        (Py_uintptr_t)((a) - 1)) & ~(Py_uintptr_t)((a) - 1)))
+/* Check if pointer "p" is aligned to "a"-bytes boundary. */
+#define _Py_IS_ALIGNED(p, a) (!((Py_uintptr_t)(p) & (Py_uintptr_t)((a) - 1)))
+
 #endif /* Py_PYMACRO_H */
@@ -10,6 +10,10 @@ What's New in Python 3.3.1
 Core and Builtins
 -----------------
 
+- Issue #15144: Fix possible integer overflow when handling pointers as
+  integer values, by using Py_uintptr_t instead of size_t.  Patch by
+  Serhiy Storchaka.
+
 - Issue #15965: Explicitly cast AT_FDCWD as (int).  Required on Solaris 10
   (which defines AT_FDCWD as 0xffd19553), harmless on other platforms.
 
 
@@ -98,7 +98,7 @@ do { memory -= size; printf("%8d - %s\n", memory, comment); } while (0)
    info. */
 #define JOIN_GET(p) ((Py_uintptr_t) (p) & 1)
 #define JOIN_SET(p, flag) ((void*) ((Py_uintptr_t) (JOIN_OBJ(p)) | (flag)))
-#define JOIN_OBJ(p) ((PyObject*) ((Py_uintptr_t) (p) & ~1))
+#define JOIN_OBJ(p) ((PyObject*) ((Py_uintptr_t) (p) & ~(Py_uintptr_t)1))
 
 /* glue functions (see the init function for details) */
 static PyObject* elementtree_parseerror_obj;
 
@@ -138,7 +138,6 @@ static int running_on_valgrind = -1;
  */
 #define ALIGNMENT               8               /* must be 2^N */
 #define ALIGNMENT_SHIFT         3
-#define ALIGNMENT_MASK          (ALIGNMENT - 1)
 
 /* Return the number of bytes in size class I, as a uint. */
 #define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT)
@@ -314,14 +313,12 @@ struct arena_object {
     struct arena_object* prevarena;
 };
 
-#undef  ROUNDUP
-#define ROUNDUP(x)              (((x) + ALIGNMENT_MASK) & ~ALIGNMENT_MASK)
-#define POOL_OVERHEAD           ROUNDUP(sizeof(struct pool_header))
+#define POOL_OVERHEAD   _Py_SIZE_ROUND_UP(sizeof(struct pool_header), ALIGNMENT)
 
 #define DUMMY_SIZE_IDX          0xffff  /* size class of newly cached pools */
 
 /* Round pointer P down to the closest pool-aligned address <= P, as a poolp */
-#define POOL_ADDR(P) ((poolp)((uptr)(P) & ~(uptr)POOL_SIZE_MASK))
+#define POOL_ADDR(P) ((poolp)_Py_ALIGN_DOWN((P), POOL_SIZE))
 
 /* Return total number of blocks in pool of size index I, as a uint. */
 #define NUMBLOCKS(I) ((uint)(POOL_SIZE - POOL_OVERHEAD) / INDEX2SIZE(I))
 
@@ -2,9 +2,6 @@
 
 #if STRINGLIB_IS_UNICODE
 
-/* Mask to check or force alignment of a pointer to C 'long' boundaries */
-#define LONG_PTR_MASK (size_t) (SIZEOF_LONG - 1)
-
 /* Mask to quickly check whether a C 'long' contains a
    non-ASCII, UTF8-encoded char. */
 #if (SIZEOF_LONG == 8)
@@ -25,7 +22,7 @@ STRINGLIB(utf8_decode)(const char **inptr, const char *end,
 {
     Py_UCS4 ch;
     const char *s = *inptr;
-    const char *aligned_end = (const char *) ((size_t) end & ~LONG_PTR_MASK);
+    const char *aligned_end = (const char *) _Py_ALIGN_DOWN(end, SIZEOF_LONG);
     STRINGLIB_CHAR *p = dest + *outpos;
 
     while (s < end) {
@@ -39,7 +36,7 @@ STRINGLIB(utf8_decode)(const char **inptr, const char *end,
                First, check if we can do an aligned read, as most CPUs have
                a penalty for unaligned reads.
             */
-            if (!((size_t) s & LONG_PTR_MASK)) {
+            if (_Py_IS_ALIGNED(s, SIZEOF_LONG)) {
                 /* Help register allocation */
                 register const char *_s = s;
                 register STRINGLIB_CHAR *_p = p;
@@ -453,7 +450,7 @@ STRINGLIB(utf16_decode)(const unsigned char **inptr, const unsigned char *e,
 {
     Py_UCS4 ch;
     const unsigned char *aligned_end =
-            (const unsigned char *) ((size_t) e & ~LONG_PTR_MASK);
+            (const unsigned char *) _Py_ALIGN_DOWN(e, SIZEOF_LONG);
     const unsigned char *q = *inptr;
     STRINGLIB_CHAR *p = dest + *outpos;
     /* Offsets from q for retrieving byte pairs in the right order. */
@@ -468,7 +465,7 @@ STRINGLIB(utf16_decode)(const unsigned char **inptr, const unsigned char *e,
         Py_UCS4 ch2;
         /* First check for possible aligned read of a C 'long'. Unaligned
            reads are more expensive, better to defer to another iteration. */
-        if (!((size_t) q & LONG_PTR_MASK)) {
+        if (_Py_IS_ALIGNED(q, SIZEOF_LONG)) {
             /* Fast path for runs of in-range non-surrogate chars. */
             register const unsigned char *_q = q;
             while (_q < aligned_end) {
@@ -565,7 +562,6 @@ STRINGLIB(utf16_decode)(const unsigned char **inptr, const unsigned char *e,
 #undef FAST_CHAR_MASK
 #undef STRIPPED_MASK
 #undef SWAB
-#undef LONG_PTR_MASK
 
 
 Py_LOCAL_INLINE(void)
@@ -588,7 +584,7 @@ STRINGLIB(utf16_encode)(unsigned short *out,
         _PyUnicode_CONVERT_BYTES(STRINGLIB_CHAR, unsigned short, in, end, out);
 # endif
     } else {
-        const STRINGLIB_CHAR *unrolled_end = in + (len & ~ (Py_ssize_t) 3);
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
         while (in < unrolled_end) {
             out[0] = SWAB2(in[0]);
             out[1] = SWAB2(in[1]);
 
@@ -43,8 +43,7 @@ STRINGLIB(fastsearch_memchr_1char)(const STRINGLIB_CHAR* s, Py_ssize_t n,
 
 #define DO_MEMCHR(memchr, s, needle, nchars) do { \
     candidate = memchr((const void *) (s), (needle), (nchars) * sizeof(STRINGLIB_CHAR)); \
-    found = (const STRINGLIB_CHAR *) \
-        ((Py_ssize_t) candidate & (~ ((Py_ssize_t) sizeof(STRINGLIB_CHAR) - 1))); \
+    found = (const STRINGLIB_CHAR *) _Py_ALIGN_DOWN(candidate, sizeof(STRINGLIB_CHAR)); \
     } while (0)
 
     if (mode == FAST_SEARCH) {
 
@@ -2,9 +2,6 @@
 
 #if STRINGLIB_IS_UNICODE
 
-/* Mask to check or force alignment of a pointer to C 'long' boundaries */
-#define LONG_PTR_MASK (size_t) (SIZEOF_LONG - 1)
-
 /* Mask to quickly check whether a C 'long' contains a
    non-ASCII, UTF8-encoded char. */
 #if (SIZEOF_LONG == 8)
@@ -21,10 +18,11 @@ Py_LOCAL_INLINE(Py_UCS4)
 STRINGLIB(find_max_char)(const STRINGLIB_CHAR *begin, const STRINGLIB_CHAR *end)
 {
     const unsigned char *p = (const unsigned char *) begin;
-    const unsigned char *aligned_end = (const unsigned char *) ((size_t) end & ~LONG_PTR_MASK);
+    const unsigned char *aligned_end =
+            (const unsigned char *) _Py_ALIGN_DOWN(end, SIZEOF_LONG);
 
     while (p < end) {
-        if (!((size_t) p & LONG_PTR_MASK)) {
+        if (_Py_IS_ALIGNED(p, SIZEOF_LONG)) {
             /* Help register allocation */
             register const unsigned char *_p = p;
             while (_p < aligned_end) {
@@ -43,7 +41,6 @@ STRINGLIB(find_max_char)(const STRINGLIB_CHAR *begin, const STRINGLIB_CHAR *end)
     return 127;
 }
 
-#undef LONG_PTR_MASK
 #undef ASCII_CHAR_MASK
 
 #else /* STRINGLIB_SIZEOF_CHAR == 1 */
@@ -72,7 +69,7 @@ STRINGLIB(find_max_char)(const STRINGLIB_CHAR *begin, const STRINGLIB_CHAR *end)
     register Py_UCS4 mask;
     Py_ssize_t n = end - begin;
     const STRINGLIB_CHAR *p = begin;
-    const STRINGLIB_CHAR *unrolled_end = begin + (n & ~ (Py_ssize_t) 3);
+    const STRINGLIB_CHAR *unrolled_end = begin + _Py_SIZE_ROUND_DOWN(n, 4);
     Py_UCS4 max_char;
 
     max_char = MAX_CHAR_ASCII;
 
@@ -159,7 +159,7 @@ extern "C" {
         const from_type *_end = (end);                  \
         Py_ssize_t n = (_end) - (_iter);                \
         const from_type *_unrolled_end =                \
-            _iter + (n & ~ (Py_ssize_t) 3);             \
+            _iter + _Py_SIZE_ROUND_DOWN(n, 4);          \
         while (_iter < (_unrolled_end)) {               \
             _to[0] = (to_type) _iter[0];                \
             _to[1] = (to_type) _iter[1];                \
@@ -4635,9 +4635,6 @@ PyUnicode_DecodeUTF8(const char *s,
 #include "stringlib/codecs.h"
 #include "stringlib/undef.h"
 
-/* Mask to check or force alignment of a pointer to C 'long' boundaries */
-#define LONG_PTR_MASK (size_t) (SIZEOF_LONG - 1)
-
 /* Mask to quickly check whether a C 'long' contains a
    non-ASCII, UTF8-encoded char. */
 #if (SIZEOF_LONG == 8)
@@ -4652,11 +4649,11 @@ static Py_ssize_t
 ascii_decode(const char *start, const char *end, Py_UCS1 *dest)
 {
     const char *p = start;
-    const char *aligned_end = (const char *) ((size_t) end & ~LONG_PTR_MASK);
+    const char *aligned_end = (const char *) _Py_ALIGN_DOWN(end, SIZEOF_LONG);
 
 #if SIZEOF_LONG <= SIZEOF_VOID_P
-    assert(!((size_t) dest & LONG_PTR_MASK));
-    if (!((size_t) p & LONG_PTR_MASK)) {
+    assert(_Py_IS_ALIGNED(dest, SIZEOF_LONG));
+    if (_Py_IS_ALIGNED(p, SIZEOF_LONG)) {
         /* Fast path, see in STRINGLIB(utf8_decode) for
            an explanation. */
         /* Help register allocation */
@@ -4682,7 +4679,7 @@ ascii_decode(const char *start, const char *end, Py_UCS1 *dest)
     while (p < end) {
         /* Fast path, see in STRINGLIB(utf8_decode) in stringlib/codecs.h
            for an explanation. */
-        if (!((size_t) p & LONG_PTR_MASK)) {
+        if (_Py_IS_ALIGNED(p, SIZEOF_LONG)) {
             /* Help register allocation */
             register const char *_p = p;
             while (_p < aligned_end) {
@@ -5390,7 +5387,7 @@ _PyUnicode_EncodeUTF16(PyObject *str,
         return NULL;
 
     /* output buffer is 2-bytes aligned */
-    assert(((Py_uintptr_t)PyBytes_AS_STRING(v) & 1) == 0);
+    assert(_Py_IS_ALIGNED(PyBytes_AS_STRING(v), 2));
     out = (unsigned short *)PyBytes_AS_STRING(v);
     if (byteorder == 0)
         *out++ = 0xFEFF;
 
@@ -71,7 +71,7 @@ fancy_roundup(int n)
  * capacity.  The code is tricky to avoid that.
  */
 #define XXXROUNDUP(n) ((n) <= 1 ? (n) :                 \
-               (n) <= 128 ? (((n) + 3) & ~3) :          \
+               (n) <= 128 ? _Py_SIZE_ROUND_UP((n), 4) : \
                fancy_roundup(n))