Fix os.urandom() using getrandom() on Linux

Issue #27278: Fix os.urandom() implementation using getrandom() on Linux.
Truncate size to INT_MAX and loop until we collected enough random bytes,
instead of casting a directly Py_ssize_t to int.

Author: vstinner

Misc/NEWS

@@ -13,6 +13,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #27278: Fix os.urandom() implementation using getrandom() on Linux.
+  Truncate size to INT_MAX and loop until we collected enough random bytes,
+  instead of casting a directly Py_ssize_t to int.
+
 - Issue #26386: Fixed ttk.TreeView selection operations with item id's
   containing spaces.
 

Python/random.c

@@ -143,7 +143,7 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise)
            to 1024 bytes */
         n = Py_MIN(size, 1024);
 #else
-        n = size;
+        n = Py_MIN(size, INT_MAX);
 #endif
 
         errno = 0;