From 6d7cd31feec58011a593cf732274a33dcc1bcb53 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 16 Jun 2020 09:54:20 -0300
Subject: [PATCH] Fixed missing GC barriers in compiler and undump

While building a new prototype, the GC needs barriers for every object
(strings and nested prototypes) that is attached to the new prototype.
---
 lparser.c |  3 +++
 lundump.c | 33 +++++++++++++++++++--------------
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/lparser.c b/lparser.c
index 37102b72..bc7d9a4f 100644
--- a/lparser.c
+++ b/lparser.c
@@ -737,6 +737,7 @@ static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
   fs->firstlabel = ls->dyd->label.n;
   fs->bl = NULL;
   f->source = ls->source;
+  luaC_objbarrier(ls->L, f, f->source);
   f->maxstacksize = 2;  /* registers 0/1 are always valid */
   enterblock(fs, bl, 0);
 }
@@ -1959,6 +1960,7 @@ static void mainfunc (LexState *ls, FuncState *fs) {
   env->idx = 0;
   env->kind = VDKREG;
   env->name = ls->envn;
+  luaC_objbarrier(ls->L, fs->f, env->name);
   luaX_next(ls);  /* read first token */
   statlist(ls);  /* parse main body */
   check(ls, TK_EOS);
@@ -1977,6 +1979,7 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
   sethvalue2s(L, L->top, lexstate.h);  /* anchor it */
   luaD_inctop(L);
   funcstate.f = cl->p = luaF_newproto(L);
+  luaC_objbarrier(L, cl, cl->p);
   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
   luaC_objbarrier(L, funcstate.f, funcstate.f->source);
   lexstate.buff = buff;
diff --git a/lundump.c b/lundump.c
index d6b249d5..77ba1955 100644
--- a/lundump.c
+++ b/lundump.c
@@ -105,30 +105,33 @@ static lua_Integer loadInteger (LoadState *S) {
 
 
 /*
-** Load a nullable string.
+** Load a nullable string into prototype 'p'.
 */
-static TString *loadStringN (LoadState *S) {
+static TString *loadStringN (LoadState *S, Proto *p) {
+  lua_State *L = S->L;
+  TString *ts;
   size_t size = loadSize(S);
-  if (size == 0)
+  if (size == 0)  /* no string? */
     return NULL;
   else if (--size <= LUAI_MAXSHORTLEN) {  /* short string? */
     char buff[LUAI_MAXSHORTLEN];
-    loadVector(S, buff, size);
-    return luaS_newlstr(S->L, buff, size);
+    loadVector(S, buff, size);  /* load string into buffer */
+    ts = luaS_newlstr(L, buff, size);  /* create string */
   }
   else {  /* long string */
-    TString *ts = luaS_createlngstrobj(S->L, size);
+    ts = luaS_createlngstrobj(L, size);  /* create string */
     loadVector(S, getstr(ts), size);  /* load directly in final place */
-    return ts;
   }
+  luaC_objbarrier(L, p, ts);
+  return ts;
 }
 
 
 /*
-** Load a non-nullable string.
+** Load a non-nullable string into prototype 'p'.
 */
-static TString *loadString (LoadState *S) {
-  TString *st = loadStringN(S);
+static TString *loadString (LoadState *S, Proto *p) {
+  TString *st = loadStringN(S, p);
   if (st == NULL)
     error(S, "bad format for constant string");
   return st;
@@ -174,7 +177,7 @@ static void loadConstants (LoadState *S, Proto *f) {
         break;
       case LUA_VSHRSTR:
       case LUA_VLNGSTR:
-        setsvalue2n(S->L, o, loadString(S));
+        setsvalue2n(S->L, o, loadString(S, f));
         break;
       default: lua_assert(0);
     }
@@ -191,6 +194,7 @@ static void loadProtos (LoadState *S, Proto *f) {
     f->p[i] = NULL;
   for (i = 0; i < n; i++) {
     f->p[i] = luaF_newproto(S->L);
+    luaC_objbarrier(S->L, f, f->p[i]);
     loadFunction(S, f->p[i], f->source);
   }
 }
@@ -229,18 +233,18 @@ static void loadDebug (LoadState *S, Proto *f) {
   for (i = 0; i < n; i++)
     f->locvars[i].varname = NULL;
   for (i = 0; i < n; i++) {
-    f->locvars[i].varname = loadStringN(S);
+    f->locvars[i].varname = loadStringN(S, f);
     f->locvars[i].startpc = loadInt(S);
     f->locvars[i].endpc = loadInt(S);
   }
   n = loadInt(S);
   for (i = 0; i < n; i++)
-    f->upvalues[i].name = loadStringN(S);
+    f->upvalues[i].name = loadStringN(S, f);
 }
 
 
 static void loadFunction (LoadState *S, Proto *f, TString *psource) {
-  f->source = loadStringN(S);
+  f->source = loadStringN(S, f);
   if (f->source == NULL)  /* no source in dump? */
     f->source = psource;  /* reuse parent's source */
   f->linedefined = loadInt(S);
@@ -310,6 +314,7 @@ LClosure *luaU_undump(lua_State *L, ZIO *Z, const char *name) {
   setclLvalue2s(L, L->top, cl);
   luaD_inctop(L);
   cl->p = luaF_newproto(L);
+  luaC_objbarrier(L, cl, cl->p);
   loadFunction(&S, cl->p, NULL);
   lua_assert(cl->nupvalues == cl->p->sizeupvalues);
   luai_verifycode(L, buff, cl->p);