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Issue #9530: Fix undefined-behaviour-inducing overflow checks in bytes and bytearray implementations.

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This commit is contained in:
Mark Dickinson 2010-08-10 18:35:01 +00:00
parent 331ea92ade
commit cf940c701f
3 changed files with 49 additions and 68 deletions
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6
Lib/test/test_bytes.py
View file

@ -220,8 +220,10 @@ def test_repeat(self):
self.assertRaises(TypeError, lambda: b * 3.14) self.assertRaises(TypeError, lambda: b * 3.14)
self.assertRaises(TypeError, lambda: 3.14 * b) self.assertRaises(TypeError, lambda: 3.14 * b)
# XXX Shouldn't bytes and bytearray agree on what to raise? # XXX Shouldn't bytes and bytearray agree on what to raise?
self.assertRaises((OverflowError, MemoryError), with self.assertRaises((OverflowError, MemoryError)):
lambda: b * sys.maxsize) c = b * sys.maxsize
with self.assertRaises((OverflowError, MemoryError)):
b *= sys.maxsize
def test_repeat_1char(self): def test_repeat_1char(self):
self.assertEqual(self.type2test(b'x')*100, self.type2test([ord('x')]*100)) self.assertEqual(self.type2test(b'x')*100, self.type2test([ord('x')]*100))

54
Objects/bytearrayobject.c
View file

@ -310,9 +310,9 @@ bytearray_repeat(PyByteArrayObject *self, Py_ssize_t count)
if (count < 0) if (count < 0)
count = 0; count = 0;
mysize = Py_SIZE(self); mysize = Py_SIZE(self);
size = mysize * count; if (count > 0 && mysize > PY_SSIZE_T_MAX / count)
if (count != 0 && size / count != mysize)
return PyErr_NoMemory(); return PyErr_NoMemory();
size = mysize * count;
result = (PyByteArrayObject *)PyByteArray_FromStringAndSize(NULL, size); result = (PyByteArrayObject *)PyByteArray_FromStringAndSize(NULL, size);
if (result != NULL && size != 0) { if (result != NULL && size != 0) {
if (mysize == 1) if (mysize == 1)
@ -335,9 +335,9 @@ bytearray_irepeat(PyByteArrayObject *self, Py_ssize_t count)
if (count < 0) if (count < 0)
count = 0; count = 0;
mysize = Py_SIZE(self); mysize = Py_SIZE(self);
size = mysize * count; if (count > 0 && mysize > PY_SSIZE_T_MAX / count)
if (count != 0 && size / count != mysize)
return PyErr_NoMemory(); return PyErr_NoMemory();
size = mysize * count;
if (size < self->ob_alloc) { if (size < self->ob_alloc) {
Py_SIZE(self) = size; Py_SIZE(self) = size;
self->ob_bytes[Py_SIZE(self)] = '\0'; /* Trailing null byte */ self->ob_bytes[Py_SIZE(self)] = '\0'; /* Trailing null byte */
@ -1505,30 +1505,28 @@ replace_interleave(PyByteArrayObject *self,
{ {
char *self_s, *result_s; char *self_s, *result_s;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, i, product; Py_ssize_t count, i;
PyByteArrayObject *result; PyByteArrayObject *result;
self_len = PyByteArray_GET_SIZE(self); self_len = PyByteArray_GET_SIZE(self);
/* 1 at the end plus 1 after every character */ /* 1 at the end plus 1 after every character;
count = self_len+1; count = min(maxcount, self_len + 1) */
if (maxcount < count) if (maxcount <= self_len)
count = maxcount; count = maxcount;
else
/* Can't overflow: self_len + 1 <= maxcount <= PY_SSIZE_T_MAX. */
count = self_len + 1;
/* Check for overflow */ /* Check for overflow */
/* result_len = count * to_len + self_len; */ /* result_len = count * to_len + self_len; */
product = count * to_len; assert(count > 0);
if (product / to_len != count) { if (to_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replace string is too long");
return NULL;
}
result_len = product + self_len;
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"replace string is too long"); "replace string is too long");
return NULL; return NULL;
} }
result_len = count * to_len + self_len;
if (! (result = (PyByteArrayObject *) if (! (result = (PyByteArrayObject *)
PyByteArray_FromStringAndSize(NULL, result_len)) ) PyByteArray_FromStringAndSize(NULL, result_len)) )
@ -1758,7 +1756,7 @@ replace_single_character(PyByteArrayObject *self,
char *self_s, *result_s; char *self_s, *result_s;
char *start, *next, *end; char *start, *next, *end;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, product; Py_ssize_t count;
PyByteArrayObject *result; PyByteArrayObject *result;
self_s = PyByteArray_AS_STRING(self); self_s = PyByteArray_AS_STRING(self);
@ -1772,16 +1770,12 @@ replace_single_character(PyByteArrayObject *self,
/* use the difference between current and new, hence the "-1" */ /* use the difference between current and new, hence the "-1" */
/* result_len = self_len + count * (to_len-1) */ /* result_len = self_len + count * (to_len-1) */
product = count * (to_len-1); assert(count > 0);
if (product / (to_len-1) != count) { if (to_len - 1 > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError, "replace bytes is too long"); PyErr_SetString(PyExc_OverflowError, "replace bytes is too long");
return NULL; return NULL;
} }
result_len = self_len + product; result_len = self_len + count * (to_len - 1);
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError, "replace bytes is too long");
return NULL;
}
if ( (result = (PyByteArrayObject *) if ( (result = (PyByteArrayObject *)
PyByteArray_FromStringAndSize(NULL, result_len)) == NULL) PyByteArray_FromStringAndSize(NULL, result_len)) == NULL)
@ -1825,7 +1819,7 @@ replace_substring(PyByteArrayObject *self,
char *self_s, *result_s; char *self_s, *result_s;
char *start, *next, *end; char *start, *next, *end;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, offset, product; Py_ssize_t count, offset;
PyByteArrayObject *result; PyByteArrayObject *result;
self_s = PyByteArray_AS_STRING(self); self_s = PyByteArray_AS_STRING(self);
@ -1842,16 +1836,12 @@ replace_substring(PyByteArrayObject *self,
/* Check for overflow */ /* Check for overflow */
/* result_len = self_len + count * (to_len-from_len) */ /* result_len = self_len + count * (to_len-from_len) */
product = count * (to_len-from_len); assert(count > 0);
if (product / (to_len-from_len) != count) { if (to_len - from_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError, "replace bytes is too long");
return NULL;
}
result_len = self_len + product;
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError, "replace bytes is too long"); PyErr_SetString(PyExc_OverflowError, "replace bytes is too long");
return NULL; return NULL;
} }
result_len = self_len + count * (to_len - from_len);
if ( (result = (PyByteArrayObject *) if ( (result = (PyByteArrayObject *)
PyByteArray_FromStringAndSize(NULL, result_len)) == NULL) PyByteArray_FromStringAndSize(NULL, result_len)) == NULL)

57
Objects/bytesobject.c
View file

@ -579,13 +579,14 @@ PyBytes_Repr(PyObject *obj, int smartquotes)
static const char *hexdigits = "0123456789abcdef"; static const char *hexdigits = "0123456789abcdef";
register PyBytesObject* op = (PyBytesObject*) obj; register PyBytesObject* op = (PyBytesObject*) obj;
Py_ssize_t length = Py_SIZE(op); Py_ssize_t length = Py_SIZE(op);
size_t newsize = 3 + 4 * length; size_t newsize;
PyObject *v; PyObject *v;
if (newsize > PY_SSIZE_T_MAX || (newsize-3) / 4 != length) { if (length > (PY_SSIZE_T_MAX - 3) / 4) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"bytes object is too large to make repr"); "bytes object is too large to make repr");
return NULL; return NULL;
} }
newsize = 3 + 4 * length;
v = PyUnicode_FromUnicode(NULL, newsize); v = PyUnicode_FromUnicode(NULL, newsize);
if (v == NULL) { if (v == NULL) {
return NULL; return NULL;
@ -732,12 +733,12 @@ bytes_repeat(register PyBytesObject *a, register Py_ssize_t n)
/* watch out for overflows: the size can overflow int, /* watch out for overflows: the size can overflow int,
* and the # of bytes needed can overflow size_t * and the # of bytes needed can overflow size_t
*/ */
size = Py_SIZE(a) * n; if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n) {
if (n && size / n != Py_SIZE(a)) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"repeated bytes are too long"); "repeated bytes are too long");
return NULL; return NULL;
} }
size = Py_SIZE(a) * n;
if (size == Py_SIZE(a) && PyBytes_CheckExact(a)) { if (size == Py_SIZE(a) && PyBytes_CheckExact(a)) {
Py_INCREF(a); Py_INCREF(a);
return (PyObject *)a; return (PyObject *)a;
@ -1687,30 +1688,28 @@ replace_interleave(PyBytesObject *self,
{ {
char *self_s, *result_s; char *self_s, *result_s;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, i, product; Py_ssize_t count, i;
PyBytesObject *result; PyBytesObject *result;
self_len = PyBytes_GET_SIZE(self); self_len = PyBytes_GET_SIZE(self);
/* 1 at the end plus 1 after every character */ /* 1 at the end plus 1 after every character;
count = self_len+1; count = min(maxcount, self_len + 1) */
if (maxcount < count) if (maxcount <= self_len)
count = maxcount; count = maxcount;
else
/* Can't overflow: self_len + 1 <= maxcount <= PY_SSIZE_T_MAX. */
count = self_len + 1;
/* Check for overflow */ /* Check for overflow */
/* result_len = count * to_len + self_len; */ /* result_len = count * to_len + self_len; */
product = count * to_len; assert(count > 0);
if (product / to_len != count) { if (to_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = product + self_len;
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long"); "replacement bytes are too long");
return NULL; return NULL;
} }
result_len = count * to_len + self_len;
if (! (result = (PyBytesObject *) if (! (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) ) PyBytes_FromStringAndSize(NULL, result_len)) )
@ -1939,7 +1938,7 @@ replace_single_character(PyBytesObject *self,
char *self_s, *result_s; char *self_s, *result_s;
char *start, *next, *end; char *start, *next, *end;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, product; Py_ssize_t count;
PyBytesObject *result; PyBytesObject *result;
self_s = PyBytes_AS_STRING(self); self_s = PyBytes_AS_STRING(self);
@ -1953,18 +1952,13 @@ replace_single_character(PyBytesObject *self,
/* use the difference between current and new, hence the "-1" */ /* use the difference between current and new, hence the "-1" */
/* result_len = self_len + count * (to_len-1) */ /* result_len = self_len + count * (to_len-1) */
product = count * (to_len-1); assert(count > 0);
if (product / (to_len-1) != count) { if (to_len - 1 > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long"); "replacement bytes are too long");
return NULL; return NULL;
} }
result_len = self_len + product; result_len = self_len + count * (to_len - 1);
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError,
"replacment bytes are too long");
return NULL;
}
if ( (result = (PyBytesObject *) if ( (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) == NULL) PyBytes_FromStringAndSize(NULL, result_len)) == NULL)
@ -2007,7 +2001,7 @@ replace_substring(PyBytesObject *self,
char *self_s, *result_s; char *self_s, *result_s;
char *start, *next, *end; char *start, *next, *end;
Py_ssize_t self_len, result_len; Py_ssize_t self_len, result_len;
Py_ssize_t count, offset, product; Py_ssize_t count, offset;
PyBytesObject *result; PyBytesObject *result;
self_s = PyBytes_AS_STRING(self); self_s = PyBytes_AS_STRING(self);
@ -2024,18 +2018,13 @@ replace_substring(PyBytesObject *self,
/* Check for overflow */ /* Check for overflow */
/* result_len = self_len + count * (to_len-from_len) */ /* result_len = self_len + count * (to_len-from_len) */
product = count * (to_len-from_len); assert(count > 0);
if (product / (to_len-from_len) != count) { if (to_len - from_len > (PY_SSIZE_T_MAX - self_len) / count) {
PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long");
return NULL;
}
result_len = self_len + product;
if (result_len < 0) {
PyErr_SetString(PyExc_OverflowError, PyErr_SetString(PyExc_OverflowError,
"replacement bytes are too long"); "replacement bytes are too long");
return NULL; return NULL;
} }
result_len = self_len + count * (to_len-from_len);
if ( (result = (PyBytesObject *) if ( (result = (PyBytesObject *)
PyBytes_FromStringAndSize(NULL, result_len)) == NULL) PyBytes_FromStringAndSize(NULL, result_len)) == NULL)