Issue #19638: Raise ValueError instead of crashing when converting billion character strings to float.
diff --git a/Python/dtoa.c b/Python/dtoa.c
index 83861ac..8996a72 100644
--- a/Python/dtoa.c
+++ b/Python/dtoa.c
@@ -204,7 +204,24 @@
MAX_ABS_EXP in absolute value get truncated to +-MAX_ABS_EXP. MAX_ABS_EXP
should fit into an int. */
#ifndef MAX_ABS_EXP
-#define MAX_ABS_EXP 19999U
+#define MAX_ABS_EXP 1100000000U
+#endif
+/* Bound on length of pieces of input strings in _Py_dg_strtod; specifically,
+ this is used to bound the total number of digits ignoring leading zeros and
+ the number of digits that follow the decimal point. Ideally, MAX_DIGITS
+ should satisfy MAX_DIGITS + 400 < MAX_ABS_EXP; that ensures that the
+ exponent clipping in _Py_dg_strtod can't affect the value of the output. */
+#ifndef MAX_DIGITS
+#define MAX_DIGITS 1000000000U
+#endif
+
+/* Guard against trying to use the above values on unusual platforms with ints
+ * of width less than 32 bits. */
+#if MAX_ABS_EXP > INT_MAX
+#error "MAX_ABS_EXP should fit in an int"
+#endif
+#if MAX_DIGITS > INT_MAX
+#error "MAX_DIGITS should fit in an int"
#endif
/* The following definition of Storeinc is appropriate for MIPS processors.
@@ -1538,6 +1555,7 @@
Long L;
BCinfo bc;
Bigint *bb, *bb1, *bd, *bd0, *bs, *delta;
+ size_t ndigits, fraclen;
dval(&rv) = 0.;
@@ -1560,40 +1578,53 @@
c = *++s;
lz = s != s1;
- /* Point s0 at the first nonzero digit (if any). nd0 will be the position
- of the point relative to s0. nd will be the total number of digits
- ignoring leading zeros. */
+ /* Point s0 at the first nonzero digit (if any). fraclen will be the
+ number of digits between the decimal point and the end of the
+ digit string. ndigits will be the total number of digits ignoring
+ leading zeros. */
s0 = s1 = s;
while ('0' <= c && c <= '9')
c = *++s;
- nd0 = nd = s - s1;
+ ndigits = s - s1;
+ fraclen = 0;
/* Parse decimal point and following digits. */
if (c == '.') {
c = *++s;
- if (!nd) {
+ if (!ndigits) {
s1 = s;
while (c == '0')
c = *++s;
lz = lz || s != s1;
- nd0 -= s - s1;
+ fraclen += (s - s1);
s0 = s;
}
s1 = s;
while ('0' <= c && c <= '9')
c = *++s;
- nd += s - s1;
+ ndigits += s - s1;
+ fraclen += s - s1;
}
- /* Now lz is true if and only if there were leading zero digits, and nd
- gives the total number of digits ignoring leading zeros. A valid input
- must have at least one digit. */
- if (!nd && !lz) {
+ /* Now lz is true if and only if there were leading zero digits, and
+ ndigits gives the total number of digits ignoring leading zeros. A
+ valid input must have at least one digit. */
+ if (!ndigits && !lz) {
if (se)
*se = (char *)s00;
goto parse_error;
}
+ /* Range check ndigits and fraclen to make sure that they, and values
+ computed with them, can safely fit in an int. */
+ if (ndigits > MAX_DIGITS || fraclen > MAX_DIGITS) {
+ if (se)
+ *se = (char *)s00;
+ goto parse_error;
+ }
+ nd = (int)ndigits;
+ nd0 = (int)ndigits - (int)fraclen;
+
/* Parse exponent. */
e = 0;
if (c == 'e' || c == 'E') {