From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 4 Sep 2020 22:56:04 +0000 (-0700)
Subject: closes bpo-41533: Fix a potential memory leak when allocating a stack (GH-21847)
X-Git-Tag: v3.9.0rc2~40
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=106c1df736d38f5b411a8571b97275d0ecf1d0a9;p=thirdparty%2FPython%2Fcpython.git

closes bpo-41533: Fix a potential memory leak when allocating a stack (GH-21847)


Free the stack allocated in va_build_stack if do_mkstack fails
and the stack is not a small_stack
(cherry picked from commit 75c80b0bda89debf312f075716b8c467d411f90e)

Co-authored-by: Tony Solomonik <tony.solomonik@gmail.com>
---

diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-08-12-20-29-57.bpo-41533.4pcVAc.rst b/Misc/NEWS.d/next/Core and Builtins/2020-08-12-20-29-57.bpo-41533.4pcVAc.rst
new file mode 100644
index 000000000000..e166f0c0b621
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-08-12-20-29-57.bpo-41533.4pcVAc.rst	
@@ -0,0 +1,2 @@
+Free the stack allocated in ``va_build_stack`` if ``do_mkstack`` fails and
+the stack is not a ``small_stack``.
diff --git a/Python/modsupport.c b/Python/modsupport.c
index 845bdcb2b6f1..13482c65083f 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -619,6 +619,9 @@ va_build_stack(PyObject **small_stack, Py_ssize_t small_stack_len,
     va_end(lva);
 
     if (res < 0) {
+        if (stack != small_stack) {
+            PyMem_Free(stack);
+        }
         return NULL;
     }