From 41c800b352149e037bdebd5f20d2f25ed2a0e2a5 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 25 Oct 2018 12:50:20 -0300
Subject: Closing methods should not interfere with returning values
A closing method cannot be called in its own stack slot, as there may
be returning values in the stack after that slot, and the call would
corrupt those values. Instead, the closing method must be copied to the
top of the stack to be called.
Moreover, even when a function returns no value, its return istruction
still has to have its position (which will set the stack top) after
the local variables, otherwise a closing method might corrupt another
not-yet-called closing method.
---
lvm.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
(limited to 'lvm.c')
diff --git a/lvm.c b/lvm.c
index 0d82756b..2a1ee175 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1452,7 +1452,8 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
vmbreak;
}
vmcase(OP_CLOSE) {
- luaF_close(L, ra, LUA_OK);
+ L->top = ra + 1; /* everything is free after this slot */
+ ProtectNT(luaF_close(L, ra, LUA_OK));
vmbreak;
}
vmcase(OP_TBC) {
@@ -1619,13 +1620,14 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
n = cast_int(L->top - ra); /* get what is available */
else
L->top = ra + n; /* set call for 'luaD_poscall' */
+ savepc(ci);
if (TESTARG_k(i)) {
int nparams1 = GETARG_C(i);
if (nparams1) /* vararg function? */
ci->func -= ci->u.l.nextraargs + nparams1;
luaF_close(L, base, LUA_OK); /* there may be open upvalues */
}
- halfProtect(luaD_poscall(L, ci, n));
+ luaD_poscall(L, ci, n);
return;
}
vmcase(OP_RETURN0) {
--
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