fix UBSAN's invalid-null-argument error in zstd_decompress.c (#1939)

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index d4d42e79447f0756c24df65b1792fc74530eb772..9e6ab216dc98a292dcd50aafc071534fb0f9ae73 100644 (file)
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1482,7 +1482,9 @@ size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize)
 MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
 {
     size_t const length = MIN(dstCapacity, srcSize);
-    memcpy(dst, src, length);
+    if (length > 0) {
+        memcpy(dst, src, length);
+    }
     return length;
 }