[Python-checkins] bpo-36856: Handle possible overflow in faulthandler_stack_overflow (GH-13205)

[Victor Stinner]

https://github.com/python/cpython/commit/6236c9823ef3e8e2229b0598d3d8189adf5e00f2
commit: 6236c9823ef3e8e2229b0598d3d8189adf5e00f2
branch: master
author: Xi Ruoyao <xry111 at mengyan1223.wang>
committer: Victor Stinner <vstinner at redhat.com>
date: 2019-05-11T19:13:23+02:00
summary:

bpo-36856: Handle possible overflow in faulthandler_stack_overflow (GH-13205)

files:
M Modules/faulthandler.c

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index d45b8660ee65..63a9b91ac469 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -1121,13 +1121,26 @@ faulthandler_stack_overflow(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
     size_t depth, size;
     uintptr_t sp = (uintptr_t)&depth;
-    uintptr_t stop;
+    uintptr_t stop, lower_limit, upper_limit;
 
     faulthandler_suppress_crash_report();
     depth = 0;
-    stop = stack_overflow(sp - STACK_OVERFLOW_MAX_SIZE,
-                          sp + STACK_OVERFLOW_MAX_SIZE,
-                          &depth);
+
+    if (STACK_OVERFLOW_MAX_SIZE <= sp) {
+        lower_limit = sp - STACK_OVERFLOW_MAX_SIZE;
+    }
+    else {
+        lower_limit = 0;
+    }
+
+    if (UINTPTR_MAX - STACK_OVERFLOW_MAX_SIZE >= sp) {
+        upper_limit = sp + STACK_OVERFLOW_MAX_SIZE;
+    }
+    else {
+        upper_limit = UINTPTR_MAX;
+    }
+
+    stop = stack_overflow(lower_limit, upper_limit, &depth);
     if (sp < stop)
         size = stop - sp;
     else