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From 74d99057a5146755e737c479850f87fd0e3b6868 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 3 Nov 2021 15:04:18 -0300
Subject: [PATCH] Bug: C stack overflow with coroutines
'coroutine.resume' did not increment counter of C calls when
continuing execution after a protected error (that is,
while running 'precover').
---
ldo.c | 6 ++++--
testes/cstack.lua | 14 ++++++++++++++
2 files changed, 18 insertions(+), 2 deletions(-)
Upstream-Status: Backport [https://github.com/lua/lua/commit/74d99057a5146755e737c479850f87fd0e3b6868.patch]
CVE: CVE-2021-43519
diff --git a/src/ldo.c b/src/ldo.c
index d0edc8b4f..66f890364 100644
--- a/src/ldo.c
+++ b/src/ldo.c
@@ -759,11 +759,10 @@ static void resume (lua_State *L, void *ud) {
StkId firstArg = L->top - n; /* first argument */
CallInfo *ci = L->ci;
if (L->status == LUA_OK) /* starting a coroutine? */
- ccall(L, firstArg - 1, LUA_MULTRET, 1); /* just call its body */
+ ccall(L, firstArg - 1, LUA_MULTRET, 0); /* just call its body */
else { /* resuming from previous yield */
lua_assert(L->status == LUA_YIELD);
L->status = LUA_OK; /* mark that it is running (again) */
- luaE_incCstack(L); /* control the C stack */
if (isLua(ci)) { /* yielded inside a hook? */
L->top = firstArg; /* discard arguments */
luaV_execute(L, ci); /* just continue running Lua code */
@@ -814,6 +813,9 @@ LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,
else if (L->status != LUA_YIELD) /* ended with errors? */
return resume_error(L, "cannot resume dead coroutine", nargs);
L->nCcalls = (from) ? getCcalls(from) : 0;
+ if (getCcalls(L) >= LUAI_MAXCCALLS)
+ return resume_error(L, "C stack overflow", nargs);
+ L->nCcalls++;
luai_userstateresume(L, nargs);
api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
status = luaD_rawrunprotected(L, resume, &nargs);
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