60 lines
2.3 KiB
Diff
60 lines
2.3 KiB
Diff
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From 42d40581dd919fb134c07027ca1ce0844c670daf Mon Sep 17 00:00:00 2001
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From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
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Date: Fri, 20 May 2022 13:14:33 -0300
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Subject: [PATCH] Save stack space while handling errors
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Because error handling (luaG_errormsg) uses slots from EXTRA_STACK,
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and some errors can recur (e.g., string overflow while creating an
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error message in 'luaG_runerror', or a C-stack overflow before calling
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the message handler), the code should use stack slots with parsimony.
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This commit fixes the bug "Lua-stack overflow when C stack overflows
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while handling an error".
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---
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ldebug.c | 5 ++++-
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lvm.c | 6 ++++--
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2 files changed, 8 insertions(+), 3 deletions(-)
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diff --git a/ldebug.c b/ldebug.c
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index a716d95e2..fa15eaf68 100644
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--- a/src/ldebug.c
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+++ b/src/ldebug.c
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@@ -824,8 +824,11 @@ l_noret luaG_runerror (lua_State *L, const char *fmt, ...) {
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va_start(argp, fmt);
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msg = luaO_pushvfstring(L, fmt, argp); /* format message */
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va_end(argp);
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- if (isLua(ci)) /* if Lua function, add source:line information */
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+ if (isLua(ci)) { /* if Lua function, add source:line information */
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luaG_addinfo(L, msg, ci_func(ci)->p->source, getcurrentline(ci));
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+ setobjs2s(L, L->top - 2, L->top - 1); /* remove 'msg' from the stack */
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+ L->top--;
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+ }
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luaG_errormsg(L);
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}
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diff --git a/lvm.c b/lvm.c
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index e8c2e9627..cd992aada 100644
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--- a/src/lvm.c
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+++ b/src/lvm.c
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@@ -656,8 +656,10 @@ void luaV_concat (lua_State *L, int total) {
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/* collect total length and number of strings */
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for (n = 1; n < total && tostring(L, s2v(top - n - 1)); n++) {
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size_t l = vslen(s2v(top - n - 1));
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- if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl))
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+ if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl)) {
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+ L->top = top - total; /* pop strings to avoid wasting stack */
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luaG_runerror(L, "string length overflow");
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+ }
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tl += l;
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}
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if (tl <= LUAI_MAXSHORTLEN) { /* is result a short string? */
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@@ -672,7 +674,7 @@ void luaV_concat (lua_State *L, int total) {
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setsvalue2s(L, top - n, ts); /* create result */
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}
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total -= n-1; /* got 'n' strings to create 1 new */
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- L->top -= n-1; /* popped 'n' strings and pushed one */
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+ L->top = top - (n - 1); /* popped 'n' strings and pushed one */
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} while (total > 1); /* repeat until only 1 result left */
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}
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