Segfault with "private" parameters inside "always" block

Segfault with "private" parameters inside "always" block

[Bart Schaefer]

zsh/param/private assumes the heap created in startparamscope() is the
only active heap until endparamscope(), but "always" blocks allocate
and free another layer of heap, which invalidates the memory "private"
uses for the parameter GSU structures.

I haven't figured out what to do about this, yet.  The GSUs can't just
be static, because different special params use different callbacks
for get/set/unset.

[PATCH] Re: Segfault with "private" parameters inside "always" block

[Bart Schaefer]

[-- Attachment #1: Type: text/plain, Size: 402 bytes --]

On Thu, Jun 9, 2022 at 2:03 PM Bart Schaefer <schaefer@brasslantern.com> wrote:
>
> zsh/param/private assumes the heap created in startparamscope() is the
> only active heap until endparamscope(), but "always" blocks allocate
> and free another layer of heap, which invalidates the memory "private"
> uses for the parameter GSU structures.

That was a lot simpler/more straightforward than I expected.

[-- Attachment #2: private_mem.txt --]
[-- Type: text/plain, Size: 1491 bytes --]

diff --git a/Src/Modules/param_private.c b/Src/Modules/param_private.c
index c53839152..065fa63d2 100644
--- a/Src/Modules/param_private.c
+++ b/Src/Modules/param_private.c
@@ -92,7 +92,7 @@ makeprivate(HashNode hn, UNUSED(int flags))
 	    makeprivate_error = 1;
 	    return;
 	}
-	struct gsu_closure *gsu = zhalloc(sizeof(struct gsu_closure));
+	struct gsu_closure *gsu = zalloc(sizeof(struct gsu_closure));
 	switch (PM_TYPE(pm->node.flags)) {
 	case PM_SCALAR:
 	    gsu->g = (void *)(pm->gsu.s);
@@ -269,6 +269,8 @@ pps_unsetfn(Param pm, int explicit)
 	gsu->unsetfn(pm, explicit);
     if (explicit)
 	pm->gsu.s = (GsuScalar)c;
+    else
+	zfree(c, sizeof(struct gsu_closure));
 }
 
 /**/
@@ -306,6 +308,8 @@ ppi_unsetfn(Param pm, int explicit)
 	gsu->unsetfn(pm, explicit);
     if (explicit)
 	pm->gsu.i = (GsuInteger)c;
+    else
+	zfree(c, sizeof(struct gsu_closure));
 }
 
 /**/
@@ -343,6 +347,8 @@ ppf_unsetfn(Param pm, int explicit)
 	gsu->unsetfn(pm, explicit);
     if (explicit)
 	pm->gsu.f = (GsuFloat)c;
+    else
+	zfree(c, sizeof(struct gsu_closure));
 }
 
 /**/
@@ -381,6 +387,8 @@ ppa_unsetfn(Param pm, int explicit)
 	gsu->unsetfn(pm, explicit);
     if (explicit)
 	pm->gsu.a = (GsuArray)c;
+    else
+	zfree(c, sizeof(struct gsu_closure));
 }
 
 static HashTable emptytable;
@@ -420,6 +428,8 @@ pph_unsetfn(Param pm, int explicit)
 	gsu->unsetfn(pm, explicit);
     if (explicit)
 	pm->gsu.h = (GsuHash)c;
+    else
+	zfree(c, sizeof(struct gsu_closure));
 }
 
 /*