[Python-checkins] bpo-40412: Nullify inittab_copy during finalization (GH-19746)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/1205afb3e10194fe22fa76385abb7e522144eb29
commit: 1205afb3e10194fe22fa76385abb7e522144eb29
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2020-05-01T16:06:23-07:00
summary:

bpo-40412: Nullify inittab_copy during finalization (GH-19746)


Otherwise we leave a dangling pointer to free'd memory. If we
then initialize a new interpreter in the same process and call
PyImport_ExtendInittab, we will (likely) crash when calling
PyMem_RawRealloc(inittab_copy, ...) since the pointer address
is bogus.

Automerge-Triggered-By: @brettcannon
(cherry picked from commit 64224a4727321a8dd33e6f769edda401193ebef0)

Co-authored-by: Gregory Szorc <gregory.szorc at gmail.com>

files:
A Misc/NEWS.d/next/C API/2020-05-01-17-28-04.bpo-40412.dE0D8N.rst
M Python/import.c

diff --git a/Misc/NEWS.d/next/C API/2020-05-01-17-28-04.bpo-40412.dE0D8N.rst b/Misc/NEWS.d/next/C API/2020-05-01-17-28-04.bpo-40412.dE0D8N.rst
new file mode 100644
index 0000000000000..92bfcddf115a6
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2020-05-01-17-28-04.bpo-40412.dE0D8N.rst	
@@ -0,0 +1 @@
+Nullify inittab_copy during finalization, preventing future interpreter initializations in an embedded situation from crashing. Patch by Gregory Szorc.
diff --git a/Python/import.c b/Python/import.c
index 495012d1c7da6..b4074d1dfc3fa 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -300,6 +300,7 @@ _PyImport_Fini2(void)
 
     /* Free memory allocated by PyImport_ExtendInittab() */
     PyMem_RawFree(inittab_copy);
+    inittab_copy = NULL;
 
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 }