mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-12-04 00:30:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

Issue #1621: Fix undefined behaviour from signed overflow in datetime module hashes, array and list iterations, and get_integer (stringlib/string_format.h)

Browse source
This commit is contained in:
Mark Dickinson 2011-09-25 15:34:32 +01:00
parent 50203a69b3
commit c7d93b7614
4 changed files with 14 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

14
Objects/stringlib/string_format.h
View file

@ -209,19 +209,17 @@ 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;
}