diff options
Diffstat (limited to 'Objects')
| -rw-r--r-- | Objects/stringlib/formatter.h | 16 | ||||
| -rw-r--r-- | Objects/stringlib/string_format.h | 15 | ||||
| -rw-r--r-- | Objects/unicodeobject.c | 4 |
3 files changed, 15 insertions, 20 deletions
diff --git a/Objects/stringlib/formatter.h b/Objects/stringlib/formatter.h index 4fdc62d650..139b56cd8e 100644 --- a/Objects/stringlib/formatter.h +++ b/Objects/stringlib/formatter.h @@ -73,7 +73,7 @@ static int get_integer(STRINGLIB_CHAR **ptr, STRINGLIB_CHAR *end, Py_ssize_t *result) { - Py_ssize_t accumulator, digitval, oldaccumulator; + Py_ssize_t accumulator, digitval; int numdigits; accumulator = numdigits = 0; for (;;(*ptr)++, numdigits++) { @@ -83,19 +83,17 @@ get_integer(STRINGLIB_CHAR **ptr, STRINGLIB_CHAR *end, if (digitval < 0) break; /* - This trick was copied from old Unicode format code. It's cute, - but would really suck on an old machine with a slow divide - implementation. Fortunately, in the normal case we do not - expect too many digits. + Detect possible overflow before it happens: + + accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if + accumulator > (PY_SSIZE_T_MAX - digitval) / 10. */ - oldaccumulator = accumulator; - accumulator *= 10; - if ((accumulator+10)/10 != oldaccumulator+1) { + if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) { PyErr_Format(PyExc_ValueError, "Too many decimal digits in format string"); return -1; } - accumulator += digitval; + accumulator = accumulator * 10 + digitval; } *result = accumulator; return numdigits; diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h index 6c7adcb01e..c46bdc2656 100644 --- a/Objects/stringlib/string_format.h +++ b/Objects/stringlib/string_format.h @@ -197,7 +197,6 @@ get_integer(const SubString *str) { Py_ssize_t accumulator = 0; Py_ssize_t digitval; - Py_ssize_t oldaccumulator; STRINGLIB_CHAR *p; /* empty string is an error */ @@ -209,19 +208,17 @@ get_integer(const SubString *str) if (digitval < 0) return -1; /* - This trick was copied from old Unicode format code. It's cute, - but would really suck on an old machine with a slow divide - implementation. Fortunately, in the normal case we do not - expect too many digits. + Detect possible overflow before it happens: + + accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if + accumulator > (PY_SSIZE_T_MAX - digitval) / 10. */ - oldaccumulator = accumulator; - accumulator *= 10; - if ((accumulator+10)/10 != oldaccumulator+1) { + if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) { PyErr_Format(PyExc_ValueError, "Too many decimal digits in format string"); return -1; } - accumulator += digitval; + accumulator = accumulator * 10 + digitval; } return accumulator; } diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c index 1dd3a852f2..3ef9c9bbaf 100644 --- a/Objects/unicodeobject.c +++ b/Objects/unicodeobject.c @@ -9648,7 +9648,7 @@ PyObject *PyUnicode_Format(PyObject *format, c = *fmt++; if (c < '0' || c > '9') break; - if ((width*10) / 10 != width) { + if (width > (PY_SSIZE_T_MAX - ((int)c - '0')) / 10) { PyErr_SetString(PyExc_ValueError, "width too big"); goto onError; @@ -9683,7 +9683,7 @@ PyObject *PyUnicode_Format(PyObject *format, c = *fmt++; if (c < '0' || c > '9') break; - if ((prec*10) / 10 != prec) { + if (prec > (INT_MAX - ((int)c - '0')) / 10) { PyErr_SetString(PyExc_ValueError, "prec too big"); goto onError; |