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Issue #1174606: Calling read() without arguments of an unbounded file 

(typically /dev/zero under Unix) could crash the interpreter.

No test as there always seems to be a risk of putting the machine on its knees.
This commit is contained in:
Antoine Pitrou 2009-03-29 00:45:26 +00:00
parent 24f3629083
commit 66994e1154
2 changed files with 17 additions and 3 deletions
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3
Misc/NEWS
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@ -43,6 +43,9 @@ Core and Builtins
Library
-------
- Issue #1174606: Calling read() without arguments of an unbounded file
(typically /dev/zero under Unix) could crash the interpreter.
- The max_buffer_size arguments of io.BufferedWriter, io.BufferedRWPair, and
io.BufferedRandom have been deprecated for removal in Python 3.2.

17
Modules/_fileio.c
View File

@ -502,9 +502,14 @@ new_buffersize(PyFileIOObject *self, size_t currentsize)
if (fstat(self->fd, &st) == 0) {
end = st.st_size;
pos = lseek(self->fd, 0L, SEEK_CUR);
if (end >= pos && pos >= 0)
/* Files claiming a size smaller than SMALLCHUNK may
actually be streaming pseudo-files. In this case, we
apply the more aggressive algorithm below.
*/
if (end >= SMALLCHUNK && pos >= 0) {
/* Add 1 so if the file were to grow we'd notice. */
return currentsize + end - pos + 1;
/* Add 1 so if the file were to grow we'd notice. */
}
}
#endif
if (currentsize > SMALLCHUNK) {
@ -533,7 +538,13 @@ fileio_readall(PyFileIOObject *self)
return NULL;
while (1) {
Py_ssize_t newsize = new_buffersize(self, total);
size_t newsize = new_buffersize(self, total);
if (newsize > PY_SSIZE_T_MAX || newsize <= 0) {
PyErr_SetString(PyExc_OverflowError,
"unbounded read returned more bytes "
"than a Python string can hold ");
return NULL;
}
if (PyBytes_GET_SIZE(result) < newsize) {
if (_PyBytes_Resize(&result, newsize) < 0) {