From 217dbe8f9ee467ab0b5831d8bf18625c46c690e9 Mon Sep 17 00:00:00 2001
From: Daniele Lacamera <root@danielinux.net>
Date: Wed, 23 Sep 2026 03:29:14 +0200
Subject: [PATCH] F-11039: zeroize XFREE'd slots in the static malloc pool

The small-stack crypto pool hands out workspace for hash blocks and
signature verification state; the slot was released back to the pool
still holding that data. Scrub it in XFREE before marking the slot
free (wc_ForceZero, same helper the rest of the crypto path uses).
---
 src/xmalloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/xmalloc.c b/src/xmalloc.c
index a270c2ff..46930e8b 100644
--- a/src/xmalloc.c
+++ b/src/xmalloc.c
@@ -26,6 +26,7 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <wolfssl/wolfcrypt/settings.h>
+#include <wolfssl/wolfcrypt/memory.h> /* wc_ForceZero */
 #ifndef USE_FAST_MATH
     #include <wolfssl/wolfcrypt/sp.h>
     #include <wolfssl/wolfcrypt/sp_int.h>
@@ -514,6 +515,9 @@ void XFREE(void *ptr, void *heap, int type)
 #endif
     while (xmalloc_pool[i].addr) {
         if ((ptr == (void *)(xmalloc_pool[i].addr)) && xmalloc_pool[i].in_use) {
+            /* Scrub the slot before releasing it: it may hold crypto
+             * workspace (hash blocks, signature verification state). */
+            wc_ForceZero(xmalloc_pool[i].addr, xmalloc_pool[i].size);
             xmalloc_pool[i].in_use = 0;
             return;
         }