From: Pip Cet <pipcet@gmail.com>
Date: Sun, 7 Mar 2021 21:26:29 +0000 (+0000)
Subject: Zero stale pointer when unloading comp units (bug#46256)
X-Git-Tag: emacs-28.0.90~2727^2~84
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=93f92cf1ba37f8b9abaee4b9487705bae464c4e0;p=emacs.git

Zero stale pointer when unloading comp units (bug#46256)

* src/alloc.c (cleanup_vector): Call unload_comp_unit.
* src/comp.c (unload_comp_unit): New function.
---

diff --git a/src/alloc.c b/src/alloc.c
index af083361770..fee8cc08aa4 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3157,8 +3157,7 @@ cleanup_vector (struct Lisp_Vector *vector)
     {
       struct Lisp_Native_Comp_Unit *cu =
 	PSEUDOVEC_STRUCT (vector, Lisp_Native_Comp_Unit);
-      eassert (cu->handle);
-      dynlib_close (cu->handle);
+      unload_comp_unit (cu);
     }
   else if (NATIVE_COMP_FLAG
 	   && PSEUDOVECTOR_TYPEP (&vector->header, PVEC_SUBR))
diff --git a/src/comp.c b/src/comp.c
index e6f672de254..e1809785410 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -4949,6 +4949,20 @@ load_comp_unit (struct Lisp_Native_Comp_Unit *comp_u, bool loading_dump,
   return res;
 }
 
+void
+unload_comp_unit (struct Lisp_Native_Comp_Unit *cu)
+{
+  if (cu->handle == NULL)
+    return;
+
+  Lisp_Object *saved_cu = dynlib_sym (cu->handle, COMP_UNIT_SYM);
+  Lisp_Object this_cu;
+  XSETNATIVE_COMP_UNIT (this_cu, cu);
+  if (EQ (this_cu, *saved_cu))
+    *saved_cu = Qnil;
+  dynlib_close (cu->handle);
+}
+
 Lisp_Object
 native_function_doc (Lisp_Object function)
 {
diff --git a/src/comp.h b/src/comp.h
index f7d17f398c7..d01bc17565d 100644
--- a/src/comp.h
+++ b/src/comp.h
@@ -78,6 +78,8 @@ extern void hash_native_abi (void);
 extern Lisp_Object load_comp_unit (struct Lisp_Native_Comp_Unit *comp_u,
 				   bool loading_dump, bool late_load);
 
+extern void unload_comp_unit (struct Lisp_Native_Comp_Unit *);
+
 extern Lisp_Object native_function_doc (Lisp_Object function);
 
 extern void syms_of_comp (void);