commit 4dfe3f98c031a05f2da84211ce857dbec514f4ae Author: Nick Mathewson <nickm@torproject.org> Date: Mon Feb 22 14:12:00 2016 -0500 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. --- lib/trunnel/CodeGen.py | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/trunnel/CodeGen.py b/lib/trunnel/CodeGen.py index 038cdd8..16047b3 100644 --- a/lib/trunnel/CodeGen.py +++ b/lib/trunnel/CodeGen.py @@ -2190,7 +2190,8 @@ class EncodeFnGenerator(CodeGenerator): self.checkAvail("elt_len", sva) self.popIndent(2) self.format(""" - memcpy(ptr, obj->{c_name}.elts_, elt_len); + if (elt_len) + memcpy(ptr, obj->{c_name}.elts_, elt_len); written += elt_len; ptr += elt_len; }}""", c_name=sva.c_name) return @@ -2597,7 +2598,8 @@ class ParseFnGenerator(CodeGenerator): self.format(""" TRUNNEL_DYNARRAY_EXPAND({tp}, &obj->{c_name}, {w}, {{}}); obj->{c_name}.n_ = {w}; - memcpy({elt}, ptr, {w}); + if ({w}) + memcpy({elt}, ptr, {w}); """, w=w, elt=elt, tp=tp, c_name=sva.c_name) self.format('ptr += {w}; remaining -= {w};\n', w=w)