Fixed bug: Negation overflow in getlocal/setlocal

roberto-ieru · roberto-ieru · commit a585eae6e7ad · 2020-07-27T12:01:38.000-03:00
diff --git a/ldebug.c b/ldebug.c
@@ -188,8 +188,8 @@ static const char *upvalname (const Proto *p, int uv) {
 static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
   if (clLvalue(s2v(ci->func))->p->is_vararg) {
     int nextra = ci->u.l.nextraargs;
-    if (n <= nextra) {
-      *pos = ci->func - nextra + (n - 1);
+    if (n >= -nextra) {  /* 'n' is negative */
+      *pos = ci->func - nextra - (n + 1);
       return "(vararg)";  /* generic name for any vararg */
     }
   }
@@ -202,7 +202,7 @@ const char *luaG_findlocal (lua_State *L, CallInfo *ci, int n, StkId *pos) {
   const char *name = NULL;
   if (isLua(ci)) {
     if (n < 0)  /* access to vararg values? */
-      return findvararg(ci, -n, pos);
+      return findvararg(ci, n, pos);
     else
       name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
   }

Original file line number	Diff line number	Diff line change
`@@ -188,8 +188,8 @@ static const char upvalname (const Proto p, int uv) {`
`188`	`188`	`static const char findvararg (CallInfo ci, int n, StkId *pos) {`
`189`	`189`	`if (clLvalue(s2v(ci->func))->p->is_vararg) {`
`190`	`190`	`int nextra = ci->u.l.nextraargs;`
`191`		`- if (n <= nextra) {`
`192`		`- *pos = ci->func - nextra + (n - 1);`
	`191`	`+ if (n >= -nextra) { /* 'n' is negative */`
	`192`	`+ *pos = ci->func - nextra - (n + 1);`
`193`	`193`	`return "(vararg)"; /* generic name for any vararg */`
`194`	`194`	`}`
`195`	`195`	`}`
`@@ -202,7 +202,7 @@ const char luaG_findlocal (lua_State L, CallInfo ci, int n, StkId pos) {`
`202`	`202`	`const char *name = NULL;`
`203`	`203`	`if (isLua(ci)) {`
`204`	`204`	`if (n < 0) /* access to vararg values? */`
`205`		`- return findvararg(ci, -n, pos);`
	`205`	`+ return findvararg(ci, n, pos);`
`206`	`206`	`else`
`207`	`207`	`name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));`
`208`	`208`	`}`