Commits

Martin von Löwis  committed 88c1e17

Backport of r61180:
Added checks for integer overflows, contributed by Google. Some are
only available if asserts are left in the code, in cases where they
can't be triggered from Python code.

  • Participants
  • Parent commits 47328d7
  • Branches 2.3

Comments (0)

Files changed (16)

File Include/pymem.h

  */
 
 #define PyMem_New(type, n) \
-	( (type *) PyMem_Malloc((n) * sizeof(type)) )
+  ( assert((n) <= PY_SIZE_MAX / sizeof(type)) , \
+	( (type *) PyMem_Malloc((n) * sizeof(type)) ) )
 #define PyMem_NEW(type, n) \
-	( (type *) PyMem_MALLOC((n) * sizeof(type)) )
+  ( assert((n) <= PY_SIZE_MAX / sizeof(type)) , \
+	( (type *) PyMem_MALLOC((n) * sizeof(type)) ) )
 
 #define PyMem_Resize(p, type, n) \
-	( (p) = (type *) PyMem_Realloc((p), (n) * sizeof(type)) )
+  ( assert((n) <= PY_SIZE_MAX / sizeof(type)) , \
+	( (p) = (type *) PyMem_Realloc((p), (n) * sizeof(type)) ) )
 #define PyMem_RESIZE(p, type, n) \
-	( (p) = (type *) PyMem_REALLOC((p), (n) * sizeof(type)) )
+  ( assert((n) <= PY_SIZE_MAX / sizeof(type)) , \
+	( (p) = (type *) PyMem_REALLOC((p), (n) * sizeof(type)) ) )
 
 /* In order to avoid breaking old code mixing PyObject_{New, NEW} with
    PyMem_{Del, DEL} and PyMem_{Free, FREE}, the PyMem "release memory"

File Include/pyport.h

 #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)."
 #endif
 
+/* Largest possible value of size_t.
+   SIZE_MAX is part of C99, so it might be defined on some
+   platforms. If it is not defined, (size_t)-1 is a portable
+   definition for C89, due to the way signed->unsigned 
+   conversion is defined. */
+#ifdef SIZE_MAX
+#define PY_SIZE_MAX SIZE_MAX
+#else
+#define PY_SIZE_MAX ((size_t)-1)
+#endif
+
 #ifdef __cplusplus
 }
 #endif
 
 (editors: check NEWS.help for information about editing NEWS using ReST.)
 
+What's New in Python 2.3.7c1?
+===========================
+
+*Release date: 02-Mar-2008*
+
+Core and builtins
+-----------------
+
+- Added checks for integer overflows, contributed by Google. Some are
+  only available if asserts are left in the code, in cases where they
+  can't be triggered from Python code.
+
+
 What's New in Python 2.3.6?
 ===========================
 

File Modules/_csv.c

 		self->field = PyMem_Malloc(self->field_size);
 	}
 	else {
+		if (self->field_size > INT_MAX / 2) {
+			PyErr_NoMemory();
+			return 0;
+		} 
 		self->field_size *= 2;
 		self->field = PyMem_Realloc(self->field, self->field_size);
 	}
 static int
 join_check_rec_size(WriterObj *self, int rec_len)
 {
+
+	if (rec_len < 0 || rec_len > INT_MAX - MEM_INCR) {
+		PyErr_NoMemory();
+		return 0;
+	}
+
 	if (rec_len > self->rec_size) {
 		if (self->rec_size == 0) {
 			self->rec_size = (rec_len / MEM_INCR + 1) * MEM_INCR;

File Modules/arraymodule.c

 		PyErr_BadArgument();
 		return NULL;
 	}
+	if (a->ob_size > INT_MAX - b->ob_size) {
+		return PyErr_NoMemory();
+	}
 	size = a->ob_size + b->ob_size;
 	np = (arrayobject *) newarrayobject(&Arraytype, size, a->ob_descr);
 	if (np == NULL) {
 	int nbytes;
 	if (n < 0)
 		n = 0;
+	if ((a->ob_size != 0) && (n > INT_MAX / a->ob_size)) {
+		return PyErr_NoMemory();
+	}
 	size = a->ob_size * n;
 	np = (arrayobject *) newarrayobject(&Arraytype, size, a->ob_descr);
 	if (np == NULL)
 			     "can only extend with array of same kind");
 		return -1;
 	}
+	if ((self->ob_size > INT_MAX - b->ob_size) ||
+		((self->ob_size + b->ob_size) > INT_MAX / self->ob_descr->itemsize)) {
+			PyErr_NoMemory();
+			return -1;
+	}
 	size = self->ob_size + b->ob_size;
         PyMem_RESIZE(self->ob_item, char, size*self->ob_descr->itemsize);
         if (self->ob_item == NULL) {
 		if (n < 0)
 			n = 0;
 		items = self->ob_item;
+		if ((self->ob_descr->itemsize != 0) && 
+			(self->ob_size > INT_MAX / self->ob_descr->itemsize)) {
+			return PyErr_NoMemory();
+		}
 		size = self->ob_size * self->ob_descr->itemsize;
 		if (n == 0) {
 			PyMem_FREE(items);
 			self->ob_size = 0;
 		}
 		else {
+			if (size > INT_MAX / n) {
+				return PyErr_NoMemory();
+			}
 			PyMem_Resize(items, char, n * size);
 			if (items == NULL)
 				return PyErr_NoMemory();
 			if ((*self->ob_descr->setitem)(self,
 					self->ob_size - n + i, v) != 0) {
 				self->ob_size -= n;
+				if (itemsize && (self->ob_size > INT_MAX / itemsize)) {
+					return PyErr_NoMemory();
+				}
 				PyMem_RESIZE(item, char,
 					          self->ob_size * itemsize);
 				self->ob_item = item;
 	n = n / itemsize;
 	if (n > 0) {
 		char *item = self->ob_item;
+		if ((n > INT_MAX - self->ob_size) ||
+			((self->ob_size + n) > INT_MAX / itemsize)) {
+				return PyErr_NoMemory();
+		}
 		PyMem_RESIZE(item, char, (self->ob_size + n) * itemsize);
 		if (item == NULL) {
 			PyErr_NoMemory();
 static PyObject *
 array_tostring(arrayobject *self, PyObject *unused)
 {
-	return PyString_FromStringAndSize(self->ob_item,
+	if (self->ob_size <= INT_MAX / self->ob_descr->itemsize) {
+		return PyString_FromStringAndSize(self->ob_item,
 				    self->ob_size * self->ob_descr->itemsize);
+	} else {
+		return PyErr_NoMemory();
+	}
 }
 
 PyDoc_STRVAR(tostring_doc,
 	}
 	if (n > 0) {
 		Py_UNICODE *item = (Py_UNICODE *) self->ob_item;
+		if (self->ob_size > INT_MAX - n) {
+			return PyErr_NoMemory();
+		}
 		PyMem_RESIZE(item, Py_UNICODE, self->ob_size + n);
 		if (item == NULL) {
 			PyErr_NoMemory();

File Modules/audioop.c

 audioop_tostereo(PyObject *self, PyObject *args)
 {
 	signed char *cp, *ncp;
-	int len, size, val1, val2, val = 0;
+	int len, new_len, size, val1, val2, val = 0;
 	double fac1, fac2, fval, maxval;
 	PyObject *rv;
 	int i;
 		return 0;
 	}
     
-	rv = PyString_FromStringAndSize(NULL, len*2);
+	new_len = len*2;
+	if (new_len < 0) {
+		PyErr_SetString(PyExc_MemoryError,
+				"not enough memory for output buffer");
+		return 0;
+	}
+
+	rv = PyString_FromStringAndSize(NULL, new_len);
 	if ( rv == 0 )
 		return 0;
 	ncp = (signed char *)PyString_AsString(rv);
 {
 	signed char *cp;
 	unsigned char *ncp;
-	int len, size, size2, val = 0;
+	int len, new_len, size, size2, val = 0;
 	PyObject *rv;
 	int i, j;
 
 		return 0;
 	}
     
-	rv = PyString_FromStringAndSize(NULL, (len/size)*size2);
+	new_len = (len/size)*size2;
+	if (new_len < 0) {
+		PyErr_SetString(PyExc_MemoryError,
+				"not enough memory for output buffer");
+		return 0;
+	}
+	rv = PyString_FromStringAndSize(NULL, new_len);
 	if ( rv == 0 )
 		return 0;
 	ncp = (unsigned char *)PyString_AsString(rv);
 	int chan, d, *prev_i, *cur_i, cur_o;
 	PyObject *state, *samps, *str, *rv = NULL;
 	int bytes_per_frame;
+	size_t alloc_size;
 
 	weightA = 1;
 	weightB = 0;
 	inrate /= d;
 	outrate /= d;
 
-	prev_i = (int *) malloc(nchannels * sizeof(int));
-	cur_i = (int *) malloc(nchannels * sizeof(int));
+	alloc_size = sizeof(int) * (unsigned)nchannels;
+	if (alloc_size < nchannels) {
+		PyErr_SetString(PyExc_MemoryError,
+				"not enough memory for output buffer");
+		return 0;
+	}
+	prev_i = (int *) malloc(alloc_size);
+	cur_i = (int *) malloc(alloc_size);
 	if (prev_i == NULL || cur_i == NULL) {
 		(void) PyErr_NoMemory();
 		goto exit;
 	unsigned char *cp;
 	unsigned char cval;
 	signed char *ncp;
-	int len, size, val;
+	int len, new_len, size, val;
 	PyObject *rv;
 	int i;
 
 		return 0;
 	}
     
-	rv = PyString_FromStringAndSize(NULL, len*size);
+	new_len = len*size;
+	if (new_len < 0) {
+		PyErr_SetString(PyExc_MemoryError,
+			"not enough memory for output buffer");
+		return 0;
+	}
+	rv = PyString_FromStringAndSize(NULL, new_len);
 	if ( rv == 0 )
 		return 0;
 	ncp = (signed char *)PyString_AsString(rv);
     
-	for ( i=0; i < len*size; i += size ) {
+	for ( i=0; i < new_len; i += size ) {
 		cval = *cp++;
 		val = st_ulaw_to_linear(cval);
 	
 {
 	signed char *cp;
 	signed char *ncp;
-	int len, size, valpred, step, delta, index, sign, vpdiff;
+	int len, new_len, size, valpred, step, delta, index, sign, vpdiff;
 	PyObject *rv, *str, *state;
 	int i, inputbuffer = 0, bufferstep;
 
 	} else if ( !PyArg_Parse(state, "(ii)", &valpred, &index) )
 		return 0;
     
-	str = PyString_FromStringAndSize(NULL, len*size*2);
+	new_len = len*size*2;
+	if (new_len < 0) {
+		PyErr_SetString(PyExc_MemoryError,
+				"not enough memory for output buffer");
+		return 0;
+	}
+	str = PyString_FromStringAndSize(NULL, new_len);
 	if ( str == 0 )
 		return 0;
 	ncp = (signed char *)PyString_AsString(str);
 	step = stepsizeTable[index];
 	bufferstep = 0;
     
-	for ( i=0; i < len*size*2; i += size ) {
+	for ( i=0; i < new_len; i += size ) {
 		/* Step 1 - get the delta value and compute next index */
 		if ( bufferstep ) {
 			delta = inputbuffer & 0xf;

File Modules/binascii.c

 	if ( !PyArg_ParseTuple(args, "t#:a2b_uu", &ascii_data, &ascii_len) )
 		return NULL;
 
+	assert(ascii_len >= 0);
+
 	/* First byte: binary data length (in bytes) */
 	bin_len = (*ascii_data++ - ' ') & 077;
 	ascii_len--;
 	if ( !PyArg_ParseTuple(args, "t#:a2b_base64", &ascii_data, &ascii_len) )
 		return NULL;
 
+	assert(ascii_len >= 0);
+
+	if (ascii_len > INT_MAX - 3)
+		return PyErr_NoMemory();
+
 	bin_len = ((ascii_len+3)/4)*3; /* Upper bound, corrected later */
 
 	/* Allocate the buffer */
 
 	if ( !PyArg_ParseTuple(args, "s#:b2a_base64", &bin_data, &bin_len) )
 		return NULL;
+
+	assert(bin_len >= 0);
+
 	if ( bin_len > BASE64_MAXBIN ) {
 		PyErr_SetString(Error, "Too much data for base64 line");
 		return NULL;
 	if ( !PyArg_ParseTuple(args, "t#:a2b_hqx", &ascii_data, &len) )
 		return NULL;
 
+	assert(len >= 0);
+
+	if (len > INT_MAX - 2)
+		return PyErr_NoMemory();
+
 	/* Allocate a string that is too big (fixed later) */
 	if ( (rv=PyString_FromStringAndSize(NULL, len)) == NULL )
 		return NULL;
 	if ( !PyArg_ParseTuple(args, "s#:rlecode_hqx", &in_data, &len) )
 		return NULL;
 
+	assert(len >= 0);
+
+	if (len > INT_MAX / 2 - 2)
+		return PyErr_NoMemory();
+
 	/* Worst case: output is twice as big as input (fixed later) */
 	if ( (rv=PyString_FromStringAndSize(NULL, len*2)) == NULL )
 		return NULL;
 	if ( !PyArg_ParseTuple(args, "s#:b2a_hqx", &bin_data, &len) )
 		return NULL;
 
+	assert(len >= 0);
+
+	if (len > INT_MAX / 2 - 2)
+		return PyErr_NoMemory();
+
 	/* Allocate a buffer that is at least large enough */
 	if ( (rv=PyString_FromStringAndSize(NULL, len*2)) == NULL )
 		return NULL;
 	if ( !PyArg_ParseTuple(args, "s#:rledecode_hqx", &in_data, &in_len) )
 		return NULL;
 
+	assert(in_len >= 0);
+
 	/* Empty string is a special case */
 	if ( in_len == 0 )
 		return Py_BuildValue("s", "");
+	else if (in_len > INT_MAX / 2)
+		return PyErr_NoMemory();
 
 	/* Allocate a buffer of reasonable size. Resized when needed */
 	out_len = in_len*2;
 #define OUTBYTE(b) \
 	do { \
 		 if ( --out_len_left < 0 ) { \
+			  if ( out_len > INT_MAX / 2) return PyErr_NoMemory(); \
 			  _PyString_Resize(&rv, 2*out_len); \
 			  if ( rv == NULL ) return NULL; \
 			  out_data = (unsigned char *)PyString_AsString(rv) \
 	if ( !PyArg_ParseTuple(args, "s#i:crc_hqx", &bin_data, &len, &crc) )
 		return NULL;
 
-	while(len--) {
+	while(len-- > 0) {
 		crc=((crc<<8)&0xff00)^crctab_hqx[((crc>>8)&0xff)^*bin_data++];
 	}
 
 	/* only want the trailing 32 bits */
 	crc &= 0xFFFFFFFFUL;
 #endif
-	while (len--)
+	while (len-- > 0)
 		crc = crc_32_tab[(crc ^ *bin_data++) & 0xffUL] ^ (crc >> 8);
 		/* Note:  (crc >> 8) MUST zero fill on left */
 
 	if (!PyArg_ParseTuple(args, "t#:b2a_hex", &argbuf, &arglen))
 		return NULL;
 
+	assert(arglen >= 0);
+	if (arglen > INT_MAX / 2)
+		return PyErr_NoMemory();
+
 	retval = PyString_FromStringAndSize(NULL, arglen*2);
 	if (!retval)
 		return NULL;
 	if (!PyArg_ParseTuple(args, "s#:a2b_hex", &argbuf, &arglen))
 		return NULL;
 
+	assert(arglen >= 0);
+
 	/* XXX What should we do about strings with an odd length?  Should
 	 * we add an implicit leading zero, or a trailing zero?  For now,
 	 * raise an exception.

File Modules/cPickle.c

 	if (self->read_func(self, &s, 4) < 0) return -1;
 
 	l = calc_binint(s, 4);
+	if (l < 0) {
+		/* Corrupt or hostile pickle -- we never write one like
+		 * this.
+		 */
+		PyErr_SetString(UnpicklingError,
+				"BINSTRING pickle has negative byte count");
+		return -1;
+	}
 
 	if (self->read_func(self, &s, l) < 0)
 		return -1;
 	if (self->read_func(self, &s, 4) < 0) return -1;
 
 	l = calc_binint(s, 4);
+	if (l < 0) {
+		/* Corrupt or hostile pickle -- we never write one like
+		 * this.
+		 */
+		PyErr_SetString(UnpicklingError,
+				"BINUNICODE pickle has negative byte count");
+		return -1;
+	}
 
 	if (self->read_func(self, &s, l) < 0)
 		return -1;

File Modules/cStringIO.c

 static PyObject *
 IO_cgetval(PyObject *self) {
         UNLESS (IO__opencheck(IOOOBJECT(self))) return NULL;
+	assert(IOOOBJECT(self)->pos >= 0);
         return PyString_FromStringAndSize(((IOobject*)self)->buf,
                                           ((IOobject*)self)->pos);
 }
         }
         else
                   s=self->string_size;
+        assert(self->pos >= 0);
         return PyString_FromStringAndSize(self->buf, s);
 }
 
         int l;
 
         UNLESS (IO__opencheck(IOOOBJECT(self))) return -1;
+        assert(IOOOBJECT(self)->pos >= 0);
+        assert(IOOOBJECT(self)->string_size >= 0);
         l = ((IOobject*)self)->string_size - ((IOobject*)self)->pos;  
         if (n < 0 || n > l) {
                 n = l;
 
         *output=((IOobject*)self)->buf + ((IOobject*)self)->pos;
         l = n - ((IOobject*)self)->buf - ((IOobject*)self)->pos;
+
+        assert(IOOOBJECT(self)->pos <= INT_MAX - l);
+        assert(IOOOBJECT(self)->pos >= 0);
+        assert(IOOOBJECT(self)->string_size >= 0);
+
         ((IOobject*)self)->pos += l;
         return l;
 }
                 n -= m;
                 self->pos -= m;
         }
+        assert(IOOOBJECT(self)->pos >= 0);
         return PyString_FromStringAndSize(output, n);
 }
 
 
         UNLESS (IO__opencheck(self)) return NULL;
 
+        assert(self->pos >= 0);
         return PyInt_FromLong(self->pos);
 }
 

File Modules/datetimemodule.c

 	char sign;
 	int none;
 
+	assert(buflen >= 1);
+
 	offset = call_utcoffset(tzinfo, tzinfoarg, &none);
 	if (offset == -1 && PyErr_Occurred())
 		return -1;
 	 * a new format.  Since computing the replacements for those codes
 	 * is expensive, don't unless they're actually used.
 	 */
+	if (PyString_Size(format) > INT_MAX - 1) {
+		PyErr_NoMemory();
+		goto Done;
+	}
+
 	totalnew = PyString_Size(format) + 1;	/* realistic if no %z/%Z */
 	newfmt = PyString_FromStringAndSize(NULL, totalnew);
 	if (newfmt == NULL) goto Done;

File Modules/rgbimgmodule.c

 	Py_Int32 *starttab = NULL, *lengthtab = NULL;
 	FILE *inf = NULL;
 	IMAGE image;
-	int y, z, tablen;
+	int y, z, tablen, new_size;
 	int xsize, ysize, zsize;
 	int bpp, rle, cur, badorder;
 	int rlebuflen;
 	zsize = image.zsize;
 	if (rle) {
 		tablen = ysize * zsize * sizeof(Py_Int32);
+		rlebuflen = (int) (1.05 * xsize +10);
+		if ((tablen / sizeof(Py_Int32)) != (ysize * zsize) ||
+		    rlebuflen < 0) {
+			PyErr_NoMemory();
+			goto finally;
+		}
+
 		starttab = (Py_Int32 *)malloc(tablen);
 		lengthtab = (Py_Int32 *)malloc(tablen);
-		rlebuflen = (int) (1.05 * xsize +10);
 		rledat = (unsigned char *)malloc(rlebuflen);
 		if (!starttab || !lengthtab || !rledat) {
 			PyErr_NoMemory();
 
 		fseek(inf, 512 + 2 * tablen, SEEK_SET);
 		cur = 512 + 2 * tablen;
+		new_size = xsize * ysize + TAGLEN;
+		if (new_size < 0 || (new_size * sizeof(Py_Int32)) < 0) {
+			PyErr_NoMemory();
+			goto finally;
+		}
+
 		rv = PyString_FromStringAndSize((char *)NULL,
-				      (xsize * ysize + TAGLEN) * sizeof(Py_Int32));
+				      new_size * sizeof(Py_Int32));
 		if (rv == NULL)
 			goto finally;
 
 			copybw((Py_Int32 *) base, xsize * ysize);
 	}
 	else {
+		new_size = xsize * ysize + TAGLEN;
+		if (new_size < 0 || (new_size * sizeof(Py_Int32)) < 0) {
+			PyErr_NoMemory();
+			goto finally;
+		}
+
 		rv = PyString_FromStringAndSize((char *) 0,
-					   (xsize*ysize+TAGLEN)*sizeof(Py_Int32));
+						new_size*sizeof(Py_Int32));
 		if (rv == NULL)
 			goto finally;
 
 		return NULL;
 	}
 	tablen = ysize * zsize * sizeof(Py_Int32);
+	rlebuflen = (int) (1.05 * xsize + 10);
+
+	if ((tablen / sizeof(Py_Int32)) != (ysize * zsize) ||
+	    rlebuflen < 0 || (xsize * sizeof(Py_Int32)) < 0) {
+		PyErr_NoMemory();
+		goto finally;
+	}
 
 	starttab = (Py_Int32 *)malloc(tablen);
 	lengthtab = (Py_Int32 *)malloc(tablen);
-	rlebuflen = (int) (1.05 * xsize + 10);
 	rlebuf = (unsigned char *)malloc(rlebuflen);
 	lumbuf = (unsigned char *)malloc(xsize * sizeof(Py_Int32));
 	if (!starttab || !lengthtab || !rlebuf || !lumbuf) {

File Modules/stropmodule.c

 	char* e;
 	char* p;
 	char* q;
-	int i, j;
+	int i, j, old_j;
 	PyObject* out;
 	char* string;
 	int stringlen;
 	}
 
 	/* First pass: determine size of output string */
-	i = j = 0; /* j: current column; i: total of previous lines */
+	i = j = old_j = 0; /* j: current column; i: total of previous lines */
 	e = string + stringlen;
 	for (p = string; p < e; p++) {
-		if (*p == '\t')
+		if (*p == '\t') {
 			j += tabsize - (j%tabsize);
-		else {
+			if (old_j > j) {
+				PyErr_SetString(PyExc_OverflowError,
+						"new string is too long");
+				return NULL;
+			}
+			old_j = j;
+		} else {
 			j++;
 			if (*p == '\n') {
 				i += j;
 		}
 	}
 
+	if ((i + j) < 0) {
+		PyErr_SetString(PyExc_OverflowError, "new string is too long");
+		return NULL;
+	}
+
 	/* Second pass: create output string and fill it */
 	out = PyString_FromStringAndSize(NULL, i+j);
 	if (out == NULL)

File Objects/bufferobject.c

 				"size must be zero or positive");
 		return NULL;
 	}
+	if (sizeof(*b) > INT_MAX - size) {
+		/* unlikely */
+		return PyErr_NoMemory();
+	}
 	/* Inline PyObject_New */
 	o = PyObject_MALLOC(sizeof(*b) + size);
 	if ( o == NULL )
 	if ( (count = (*pb->bf_getreadbuffer)(other, 0, &p2)) < 0 )
 		return NULL;
 
+	assert(count <= PY_SIZE_MAX - self->b_size);
+
 	ob = PyString_FromStringAndSize(NULL, self->b_size + count);
 	p1 = PyString_AS_STRING(ob);
 	memcpy(p1, self->b_ptr, self->b_size);

File Objects/listobject.c

 		return NULL;
 	}
 	nbytes = size * sizeof(PyObject *);
-	/* Check for overflow */
-	if (nbytes / sizeof(PyObject *) != (size_t)size) {
+	/* Check for overflow without an actual overflow,
+	 *  which can cause compiler to optimise out */
+	if (size > PY_SIZE_MAX / sizeof(PyObject *)) {
 		return PyErr_NoMemory();
 	}
 	op = PyObject_GC_New(PyListObject, &PyList_Type);
 	 * we don't care what's in the block.
 	 */
 	merge_freemem(ms);
+	if (need > INT_MAX / sizeof(PyObject*)) {
+		PyErr_NoMemory();
+		return -1;
+	}
 	ms->a = (PyObject **)PyMem_Malloc(need * sizeof(PyObject*));
 	if (ms->a) {
 		ms->alloced = need;
 				return 0;
 			}
 
+			assert(slicelength <= PY_SIZE_MAX / sizeof(PyObject*));
+
 			garbage = (PyObject**)
 				PyMem_MALLOC(slicelength*sizeof(PyObject*));
 

File Parser/node.c

 	if (current_capacity < 0 || required_capacity < 0)
 		return E_OVERFLOW;
 	if (current_capacity < required_capacity) {
+		if (required_capacity > PY_SIZE_MAX / sizeof(node)) {
+			return E_NOMEM;
+		}
 		n = n1->n_child;
 		n = (node *) PyObject_REALLOC(n,
 					      required_capacity * sizeof(node));

File Python/bltinmodule.c

 					PyString_AS_STRING(item)[0];
 			} else {
 				/* do we need more space? */
-				int need = j + reslen + len-i-1;
+				int need = j;
+
+				/* calculate space requirements while checking for overflow */
+				if (need > INT_MAX - reslen) {
+					Py_DECREF(item);
+					goto Fail_1;
+				}
+
+				need += reslen;
+
+				if (need > INT_MAX - len) {
+					Py_DECREF(item);
+					goto Fail_1;
+				}
+
+				need += len;
+
+				if (need <= i) {
+					Py_DECREF(item);
+					goto Fail_1;
+				}
+
+				need = need - i - 1;
+
+				assert(need >= 0);
+				assert(outlen >= 0);
+
 				if (need > outlen) {
 					/* overallocate, to avoid reallocations */
-					if (need<2*outlen)
+					if (outlen > INT_MAX / 2) {
+						Py_DECREF(item);
+						return NULL;
+					}
+
+					if (need<2*outlen) {
 						need = 2*outlen;
+          }
 					if (_PyString_Resize(&result, need)) {
 						Py_DECREF(item);
 						return NULL;
 			} else {
 				/* do we need more space? */
 				int need = j + reslen + len-i-1;
+        
+				/* check that didnt overflow */
+				if ((j > INT_MAX - reslen) ||
+					((j + reslen) > INT_MAX - len) ||
+						((j + reslen + len) < i) ||
+							((j + reslen + len - i) <= 0)) {
+					Py_DECREF(item);
+					return NULL;
+				}
+
+				assert(need >= 0);
+				assert(outlen >= 0);
+				
 				if (need > outlen) {
 					/* overallocate, to avoid reallocations */
-					if (need<2*outlen)
-						need = 2*outlen;
+					if (need < 2 * outlen) {
+						if (outlen > INT_MAX / 2) {
+							Py_DECREF(item);
+							return NULL;
+						} else {
+							need = 2 * outlen;
+						}
+					}
+
 					if (PyUnicode_Resize(&result, need)) {
 						Py_DECREF(item);
 						goto Fail_1;