From 17f725fe0d7ef52c5538782d2adf9dbce8d25916 Mon Sep 17 00:00:00 2001
From: Erik Torres Aguilar <ertorres@microsoft.com>
Date: Wed, 9 Dec 2020 19:35:39 +0000
Subject: [PATCH] ICU-21118 check that dst and src are not null in uprv_memcpy

See #1489
---
 icu4c/source/common/cmemory.h    | 15 +++++++++++++--
 icu4c/source/common/uloc_tag.cpp |  5 ++++-
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/icu4c/source/common/cmemory.h b/icu4c/source/common/cmemory.h
index a9d9424b4e2..f70587a4e3d 100644
--- a/icu4c/source/common/cmemory.h
+++ b/icu4c/source/common/cmemory.h
@@ -31,14 +31,25 @@
 #include <stddef.h>
 #include <string.h>
 #include "unicode/localpointer.h"
+#include "uassert.h"
 
 #if U_DEBUG && defined(UPRV_MALLOC_COUNT)
 #include <stdio.h>
 #endif
 
 
-#define uprv_memcpy(dst, src, size) U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size)
-#define uprv_memmove(dst, src, size) U_STANDARD_CPP_NAMESPACE memmove(dst, src, size)
+#define uprv_memcpy(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    U_STANDARD_CPP_NAMESPACE memcpy(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+
+#define uprv_memmove(dst, src, size) UPRV_BLOCK_MACRO_BEGIN { \
+    U_ASSERT(dst != NULL); \
+    U_ASSERT(src != NULL); \
+    U_STANDARD_CPP_NAMESPACE memmove(dst, src, size); \
+} UPRV_BLOCK_MACRO_END
+
 
 /**
  * \def UPRV_LENGTHOF
diff --git a/icu4c/source/common/uloc_tag.cpp b/icu4c/source/common/uloc_tag.cpp
index ee1cedf30e5..0bd4b85e2c0 100644
--- a/icu4c/source/common/uloc_tag.cpp
+++ b/icu4c/source/common/uloc_tag.cpp
@@ -2047,7 +2047,10 @@ ultag_parse(const char* tag, int32_t tagLen, int32_t* parsedLen, UErrorCode* sta
         *status = U_MEMORY_ALLOCATION_ERROR;
         return NULL;
     }
-    uprv_memcpy(tagBuf, tag, tagLen);
+    
+    if (tagLen > 0) {
+        uprv_memcpy(tagBuf, tag, tagLen);
+    }
     *(tagBuf + tagLen) = 0;
 
     /* create a ULanguageTag */