Repository navigation
Unchecked signed integer overflow in PyLong_AsPid() #117021
Description
If pid_t has the same size as int, PyLong_AsPid is defined as PyLong_AsLong. if the size of int is less than the size of long, there are values out of the C int range but in the C long range. Calling PyLong_AsPid() with such argument will not raise an exception, but casting the result out of the C int range to pid_t has undefined behavior.
Most non-Windows 64-bit platforms are affected.
The simplest solution is to define PyLong_AsPid as PyLong_AsInt. It only applicable in 3.13, because PyLong_AsInt is new in 3.13. In older versions there is _PyLong_AsInt, but it is declared in Include/cpython/longobject.h, not in Include/longobject.h.
Linked PRs
- gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windows 64-bit platforms #117064
- [3.12] gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windows 64-bit platforms (GH-117064) #117070
- [3.11] gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windows 64-bit platforms (GH-117064) (GH-117070) #117075
Activity
pitrou commentedon Mar 19, 2024
Not sure what you mean by "define" PyLong_AsPid, but if you mean
#define, then I think a real function should be exposed instead, for the benefits of non-C/C++ users.serhiy-storchaka commentedon Mar 19, 2024
Currently it is defined by
#define.vstinner commentedon Mar 19, 2024
I don't get thr context of this issue. Which functions are you modifying? In which code? Is it related to Argument Clinic?
serhiy-storchaka commentedon Mar 19, 2024
There are also other definitions in different branches, but they are okay.
It could be defined as
Still not good if Py_LIMITED_API < 0x030d0000, but it is the best that can be done with the limited C API.
On other hand, the status of
PyLong_AsPidis unclear. It is not documented, not even mentioned in changelogs, but de-facto it is always available, independently from the Py_LIMITED_API setting. It was added by @gpshead in fb94c5f. Perhaps it should be treated as a private C API, but its name is not underscored.Similar functions
PyLong_FromSocket_tandPyLong_AsSocket_twere made public, but than were made private again.serhiy-storchaka commentedon Mar 19, 2024
Opened a discussion about status of
PyLong_FromPidandPyLong_AsPid: https://discuss.python.org/t/status-of-pylong-frompid-and-pylong-aspid/48988.pythongh-117021: Fix integer overflow in PyLong_AsPid() on non-Window…
gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windows 64-b…
pythongh-117021: Fix integer overflow in PyLong_AsPid() on non-Window…
[3.12] pythongh-117021: Fix integer overflow in PyLong_AsPid() on non…
[3.12] gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windo…
[3.11] [3.12] pythongh-117021: Fix integer overflow in PyLong_AsPid()…
[3.11] gh-117021: Fix integer overflow in PyLong_AsPid() on non-Windo…
pythongh-117021: Fix integer overflow in PyLong_AsPid() on non-Window…
Squashed commit of the following:
Squashed commit of the following:
pythongh-117021: Fix integer overflow in PyLong_AsPid() on non-Window…