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Fixed bug: invalid 'oldpc' when returning to a function

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The field 'L->oldpc' is not always updated when control returns to a
function; an invalid value can seg. fault when computing 'changedline'.
(One example is an error in a finalizer; control can return to
'luaV_execute' without executing 'luaD_poscall'.) Instead of trying to
fix all possible corner cases, it seems safer to be resilient to invalid
values for 'oldpc'. Valid but wrong values at most cause an extra call
to a line hook.
This commit is contained in:
Roberto Ierusalimschy
2020-07-17 11:01:05 -03:00
parent 1ecfbfa1a1
commit a2195644d8
6 changed files with 36 additions and 21 deletions
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6
ldo.c
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@@ -327,7 +327,7 @@ static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
ptrdiff_t oldtop = savestack(L, L->top); /* hook may change top */
int delta = 0;
if (isLuacode(ci)) {
Proto *p = clLvalue(s2v(ci->func))->p;
Proto *p = ci_func(ci)->p;
if (p->is_vararg)
delta = ci->u.l.nextraargs + p->numparams + 1;
if (L->top < ci->top)
@@ -340,8 +340,8 @@ static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */
ci->func -= delta;
}
if (isLua(ci->previous))
L->oldpc = ci->previous->u.l.savedpc; /* update 'oldpc' */
if (isLua(ci = ci->previous))
L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p); /* update 'oldpc' */
return restorestack(L, oldtop);
}