commit 1442fd57836851df5b4d67c30d3be77021768a52
author Roberto Ierusalimschy <roberto@inf.puc-rio.br> Mon Jul 13 16:10:31 2020 -0300
committer Roberto Ierusalimschy <roberto@inf.puc-rio.br> Mon Jul 13 16:10:31 2020 -0300
tree c34201097ffe7612008dbf1aecf26e934d3a8352
parent e398e03aa90546925416f41508dba9709151a1c2

Bug fix: GC step can destroy a preallocated CallInfo

Macro 'checkstackp' also does a GC step, which could remove the
preallocated CallInfo when calling a function.

ldo.c

diff --git a/ldo.c b/ldo.c
index b39be1b..f4b1705 100644
--- a/ldo.c
+++ b/ldo.c
@@ -466,13 +466,13 @@
       f = fvalue(s2v(func));
      Cfunc: {
       int n;  /* number of returns */
-      CallInfo *ci = next_ci(L);
+      CallInfo *ci;
       checkstackp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
+      L->ci = ci = next_ci(L);
       ci->nresults = nresults;
       ci->callstatus = CIST_C;
       ci->top = L->top + LUA_MINSTACK;
       ci->func = func;
-      L->ci = ci;
       lua_assert(ci->top <= L->stack_last);
       if (L->hookmask & LUA_MASKCALL) {
         int narg = cast_int(L->top - func) - 1;
@@ -486,18 +486,18 @@
       break;
     }
     case LUA_VLCL: {  /* Lua function */
-      CallInfo *ci = next_ci(L);
+      CallInfo *ci;
       Proto *p = clLvalue(s2v(func))->p;
       int narg = cast_int(L->top - func) - 1;  /* number of real arguments */
       int nfixparams = p->numparams;
       int fsize = p->maxstacksize;  /* frame size */
       checkstackp(L, fsize, func);
+      L->ci = ci = next_ci(L);
       ci->nresults = nresults;
       ci->u.l.savedpc = p->code;  /* starting point */
       ci->callstatus = 0;
       ci->top = func + 1 + fsize;
       ci->func = func;
-      L->ci = ci;
       for (; narg < nfixparams; narg++)
         setnilvalue(s2v(L->top++));  /* complete missing arguments */
       lua_assert(ci->top <= L->stack_last);