Commit 4dfe3f98 authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

In generated code, never pass NULL to memcpy even with length 0 

The C standard says that you can never say memcpy(x, NULL, 0), even
though most libcs permit it.

Found with asan.
parent 0795ce5e

lib/trunnel/CodeGen.py

+4 −2
Original line number Diff line number Diff line
@@ -2190,6 +2190,7 @@ class EncodeFnGenerator(CodeGenerator): 
            self.checkAvail("elt_len", sva)

            self.popIndent(2)

            self.format("""

                    if (elt_len)

                      memcpy(ptr, obj->{c_name}.elts_, elt_len);

                    written += elt_len; ptr += elt_len;

                  }}""", c_name=sva.c_name)
@@ -2597,6 +2598,7 @@ class ParseFnGenerator(CodeGenerator): 
                self.format("""

                    TRUNNEL_DYNARRAY_EXPAND({tp}, &obj->{c_name}, {w}, {{}});

                    obj->{c_name}.n_ = {w};

                    if ({w})

                      memcpy({elt}, ptr, {w});

                    """, w=w, elt=elt, tp=tp, c_name=sva.c_name)