[Bug demangler/110147] UBSAN error in rust-demangle.c: NULL pointer passed to memcpy

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110147

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
--- a/libiberty/rust-demangle.c
+++ b/libiberty/rust-demangle.c
@@ -1569,8 +1569,11 @@ str_buf_append (struct str_buf *buf, const char *data,
size_t len)
   if (buf->errored)
     return;

-  memcpy (buf->ptr + buf->len, data, len);
-  buf->len += len;
+  if (len)
+  {
+    memcpy (buf->ptr + buf->len, data, len);
+    buf->len += len;
+  }
 }

 static void