From 1d300ce1d8238136595c8fea76266a4755cd73a2 Mon Sep 17 00:00:00 2001
From: "Gregory P. Smith" <greg@krypto.org>
Date: Sun, 30 Dec 2018 21:13:02 -0800
Subject: [PATCH] bpo-35214: Annotate posix calls for clang MSan. (#11389)

It doesn't know the details of a few less common libc functions.
---
 .../2018-12-30-15-36-23.bpo-35214.GWDQcv.rst     |  2 +-
 Modules/posixmodule.c                            | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-12-30-15-36-23.bpo-35214.GWDQcv.rst b/Misc/NEWS.d/next/Core and Builtins/2018-12-30-15-36-23.bpo-35214.GWDQcv.rst
index 62dee0e3700..fa61f78a932 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2018-12-30-15-36-23.bpo-35214.GWDQcv.rst	
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-12-30-15-36-23.bpo-35214.GWDQcv.rst	
@@ -1,2 +1,2 @@
 clang Memory Sanitizer build instrumentation was added to work around false
-positives from socket, time, test_io, and test_faulthandler.
+positives from posix, socket, time, test_io, and test_faulthandler.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 4ff1694c583..e5c2a9cfc1e 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -367,6 +367,10 @@ static int win32_can_symlink = 0;
 #define HAVE_STRUCT_STAT_ST_FSTYPE 1
 #endif
 
+#ifdef _Py_MEMORY_SANITIZER
+# include <sanitizer/msan_interface.h>
+#endif
+
 #ifdef HAVE_FORK
 static void
 run_at_forkers(PyObject *lst, int reverse)
@@ -5493,6 +5497,9 @@ os_posix_spawn_impl(PyObject *module, path_t *path, PyObject *argv,
         PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, path->object);
         goto exit;
     }
+#ifdef _Py_MEMORY_SANITIZER
+    __msan_unpoison(&pid, sizeof(pid));
+#endif
     result = PyLong_FromPid(pid);
 
 exit:
@@ -6098,6 +6105,9 @@ os_sched_rr_get_interval_impl(PyObject *module, pid_t pid)
         posix_error();
         return -1.0;
     }
+#ifdef _Py_MEMORY_SANITIZER
+    __msan_unpoison(&interval, sizeof(interval));
+#endif
     return (double)interval.tv_sec + 1e-9*interval.tv_nsec;
 }
 #endif /* HAVE_SCHED_RR_GET_INTERVAL */
@@ -6568,6 +6578,12 @@ posix_getgrouplist(PyObject *self, PyObject *args)
         return posix_error();
     }
 
+#ifdef _Py_MEMORY_SANITIZER
+    /* Clang memory sanitizer libc intercepts don't know getgrouplist. */
+    __msan_unpoison(&ngroups, sizeof(ngroups));
+    __msan_unpoison(groups, ngroups*sizeof(*groups));
+#endif
+
     list = PyList_New(ngroups);
     if (list == NULL) {
         PyMem_Del(groups);