From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 7E90424F35 for ; Mon, 4 Feb 2019 22:29:37 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mY_EumriRZvY for ; Mon, 4 Feb 2019 22:29:37 -0500 (EST) Received: from smtp41.i.mail.ru (smtp41.i.mail.ru [94.100.177.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTPS id BFA11222F7 for ; Mon, 4 Feb 2019 22:29:36 -0500 (EST) Date: Tue, 5 Feb 2019 06:29:30 +0300 From: Alexander Turenko Subject: [tarantool-patches] Re: [PATCH v2 1/3] lua-yaml: verify arguments count Message-ID: <20190205032929.gbcapbbgbnpfolnl@tkn_work_nb> References: <58ccdb031d0befd0e80d50a4684f5e7a59182062.1548123025.git.alexander.turenko@tarantool.org> <04a54285-aa7c-2726-0077-64c14a40dde6@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <04a54285-aa7c-2726-0077-64c14a40dde6@tarantool.org> Sender: tarantool-patches-bounce@freelists.org Errors-to: tarantool-patches-bounce@freelists.org Reply-To: tarantool-patches@freelists.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: tarantool-patches List-subscribe: List-owner: List-post: List-archive: To: Vladislav Shpilevoy Cc: tarantool-patches@freelists.org, AKhatskevich Hi! See answers below. I'll send the updated patchset as v3 soon. WBR, Alexander Turenko. On Fri, Jan 25, 2019 at 12:26:53AM +0300, Vladislav Shpilevoy wrote: > Thanks for the patch! > > On 22/01/2019 05:12, Alexander Turenko wrote: > > From: AKhatskevich > > > > Added arguments count check for yaml.encode() and decode.decode() > > Typo: 'decode.decode' -> 'yaml.decode'. Thx. Fixed. > > > functions. > > > > Without these checks the functions could read garbage outside of a Lua > > stack when called w/o arguments. > > Honestly, I do not understand how is it possible. Please, > provide a test for both functions. See my 3 doubts below. lua_isstring(L, 1) checks a garbage w/o preliminary lua_gettop() check. yaml.encode() gives me "unsupported Lua type 'thread'" on the current tarantool 2.1. Anyway, added bad API usage test cases. Also I changed this: diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc index 3a427263e..46374970f 100644 --- a/third_party/lua-yaml/lyaml.cc +++ b/third_party/lua-yaml/lyaml.cc @@ -453,7 +453,7 @@ usage_error: return luaL_error(L, OOM_ERRMSG); yaml_parser_set_input_string(&loader.parser, (yaml_char_t *) document, len); bool tag_only; - if (lua_gettop(L) == 2) { + if (lua_gettop(L) == 2 && ! lua_isnil(L, 2)) { if (! lua_istable(L, 2)) goto usage_error; lua_getfield(L, 2, "tag_only"); We should not raise an usage error for yaml.decode(object, nil). > > > --- > > third_party/lua-yaml/lyaml.cc | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc > > index c6d118a79..9b07992d8 100644 > > --- a/third_party/lua-yaml/lyaml.cc > > +++ b/third_party/lua-yaml/lyaml.cc > > @@ -400,7 +400,8 @@ static void load(struct lua_yaml_loader *loader) { > > */ > > static int l_load(lua_State *L) { > > struct lua_yaml_loader loader; > > - if (! lua_isstring(L, 1)) { > > + int top = lua_gettop(L); > > + if (!(top == 1 || top == 2) || !lua_isstring(L, 1)) { > > 1. How could the old code lead to a bug, if there was a > check if the first argument is a string? The second argument It does not check a stack top (arguments count). > is not used until the next hunk, about which see my next > comment As I see it is usual way to write such functions: check whether count of arguments and types of mandatory arguments are valid at start of the function. > > > usage_error: > > return luaL_error(L, "Usage: yaml.decode(document, "\ > > "[{tag_only = boolean}])"); > > @@ -416,7 +417,7 @@ usage_error: > > return luaL_error(L, OOM_ERRMSG); > > yaml_parser_set_input_string(&loader.parser, (yaml_char_t *) document, len); > > bool tag_only; > > - if (lua_gettop(L) > 1) { > > + if (lua_gettop(L) == 2) { > > 2. This function never touches anything beyond second value on > the stack, so here lua_gettop(L) > 1 means the same as > lua_gettop(L) == 2 - the second argument exist. Third and next > values do not matter. I read this as 'those are equivalent' (correct me if I'm wrong). Ok. I'd prefer to leave it with ==. Also note the fix I pasted above. > > > if (! lua_istable(L, 2)) > > goto usage_error; > > lua_getfield(L, 2, "tag_only"); > > @@ -794,7 +795,7 @@ error: > > static int l_dump(lua_State *L) { > > struct luaL_serializer *serializer = luaL_checkserializer(L); > > int top = lua_gettop(L); > > - if (top > 2) { > > + if (!(top == 1 || top == 2)) { > > 3. Here my reasoning is the same - the previous checking works > as well. It will not give an error in case of yaml.encode() and yaml.encode({}, {}, {}). > > > usage_error: > > return luaL_error(L, "Usage: encode(object, {tag_prefix = , "\ > > "tag_handle = })"); > >