Prevent expandtabs() on string and unicode objects from causing a segfault when
a large width is passed on 32-bit platforms. Found by Google.
It would be good for people to review this especially carefully and verify
I don't have an off by one error and there is no other way to cause overflow.
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 63e1381..d7ad5cc 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -3307,7 +3307,7 @@
{
const char *e, *p;
char *q;
- Py_ssize_t i, j;
+ Py_ssize_t i, j, old_j;
PyObject *u;
int tabsize = 8;
@@ -3315,12 +3315,18 @@
return NULL;
/* First pass: determine size of output string */
- i = j = 0;
+ i = j = old_j = 0;
e = PyString_AS_STRING(self) + PyString_GET_SIZE(self);
for (p = PyString_AS_STRING(self); p < e; p++)
if (*p == '\t') {
- if (tabsize > 0)
+ if (tabsize > 0) {
j += tabsize - (j % tabsize);
+ if (old_j > j) {
+ PyErr_SetString(PyExc_OverflowError, "new string is too long");
+ return NULL;
+ }
+ old_j = j;
+ }
}
else {
j++;
@@ -3330,6 +3336,11 @@
}
}
+ if ((i + j) < 0) {
+ PyErr_SetString(PyExc_OverflowError, "new string is too long");
+ return NULL;
+ }
+
/* Second pass: create output string and fill it */
u = PyString_FromStringAndSize(NULL, i + j);
if (!u)