From e4607523234f16ed9ed0436340b9315377dbfe7f Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Mon, 2 Mar 2020 13:24:06 -0300 Subject: [PATCH] Fixed "conceptual" bug in 'luaK_setreturns' This function was computing invalid instruction addresses when the expression was not a multi-return instruction. (Virtually all machines don't raise errors when computing an invalid address, as long as the address is not accessed, but this computation is undefined behavior in ISO C.) --- lcode.c | 7 +++---- lparser.c | 3 ++- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/lcode.c b/lcode.c index 83a6d064..6f241c94 100644 --- a/lcode.c +++ b/lcode.c @@ -703,19 +703,18 @@ static void const2exp (TValue *v, expdesc *e) { /* ** Fix an expression to return the number of results 'nresults'. -** Either 'e' is a multi-ret expression (function call or vararg) -** or 'nresults' is LUA_MULTRET (as any expression can satisfy that). +** 'e' must be a multi-ret expression (function call or vararg). */ void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) { Instruction *pc = &getinstruction(fs, e); if (e->k == VCALL) /* expression is an open function call? */ SETARG_C(*pc, nresults + 1); - else if (e->k == VVARARG) { + else { + lua_assert(e->k == VVARARG); SETARG_C(*pc, nresults + 1); SETARG_A(*pc, fs->freereg); luaK_reserveregs(fs, 1); } - else lua_assert(nresults == LUA_MULTRET); } diff --git a/lparser.c b/lparser.c index 8c812039..b0dbb65c 100644 --- a/lparser.c +++ b/lparser.c @@ -1014,7 +1014,8 @@ static void funcargs (LexState *ls, expdesc *f, int line) { args.k = VVOID; else { explist(ls, &args); - luaK_setmultret(fs, &args); + if (hasmultret(args.k)) + luaK_setmultret(fs, &args); } check_match(ls, ')', '(', line); break;