Addressing PR comments

IDE/CRYPTOCELL/user_settings.h

@@ -401,6 +401,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/GCC-ARM/Header/user_settings.h

@@ -419,6 +419,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/NETOS/user_settings.h

@@ -410,6 +410,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h> /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/RISCV/SIFIVE-HIFIVE1/user_settings.h

@@ -397,6 +397,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/STARCORE/user_settings.h

@@ -417,6 +417,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h> /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/SimplicityStudio/user_settings.h

@@ -337,6 +337,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/WICED-STUDIO/user_settings.h

@@ -411,6 +411,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/WINCE/user_settings.h

@@ -491,6 +491,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/XCODE-FIPSv2/macOS-C++/Intel/user_settings.h

@@ -407,6 +407,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/XCODE-FIPSv2/macOS-C++/M1/user_settings.h

@@ -418,6 +418,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/XCODE-FIPSv2/user_settings.h

@@ -419,6 +419,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

IDE/XCODE-FIPSv5/user_settings.h

@@ -500,6 +500,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

examples/configs/user_settings_template.h

@@ -354,6 +354,7 @@ extern "C" {
 
     /* prototypes for user heap override functions */
     /* Note: Realloc only required for normal math */
+    /* Note2: XFREE(NULL) must be properly handled */
     #include <stddef.h>  /* for size_t */
     extern void *myMalloc(size_t n, void* heap, int type);
     extern void myFree(void *p, void* heap, int type);

wolfssl/wolfcrypt/types.h

@@ -437,7 +437,13 @@ typedef struct w64wrapper {
     /* idea to add global alloc override by Moises Guimaraes  */
     /* default to libc stuff */
     /* XREALLOC is used once in normal math lib, not in fast math lib */
-    /* XFREE on some embedded systems doesn't like free(0) so test  */
+    /* XFREE on some embedded systems doesn't like free(0) so test for NULL
+     * explicitly.
+     *
+     * For example:
+     *   #define XFREE(p, h, t) \
+     *      {void* xp = (p); if (xp != NULL) free(xp, h, t);}
+     */
     #if defined(HAVE_IO_POOL)
         WOLFSSL_API void* XMALLOC(size_t n, void* heap, int type);
         WOLFSSL_API void* XREALLOC(void *p, size_t n, void* heap, int type);