| From 42d40581dd919fb134c07027ca1ce0844c670daf Mon Sep 17 00:00:00 2001 |
| From: Roberto Ierusalimschy <roberto@inf.puc-rio.br> |
| Date: Fri, 20 May 2022 13:14:33 -0300 |
| Subject: [PATCH] Save stack space while handling errors |
| |
| Because error handling (luaG_errormsg) uses slots from EXTRA_STACK, |
| and some errors can recur (e.g., string overflow while creating an |
| error message in 'luaG_runerror', or a C-stack overflow before calling |
| the message handler), the code should use stack slots with parsimony. |
| |
| This commit fixes the bug "Lua-stack overflow when C stack overflows |
| while handling an error". |
| |
| CVE: CVE-2022-33099 |
| |
| Upstream-Status: Backport [https://github.com/lua/lua/commit/42d40581dd919fb134c07027ca1ce0844c670daf] |
| |
| Signed-off-by: Khem Raj <raj.khem@gmail.com> |
| --- |
| ldebug.c | 5 ++++- |
| lvm.c | 6 ++++-- |
| 2 files changed, 8 insertions(+), 3 deletions(-) |
| |
| --- a/src/ldebug.c |
| +++ b/src/ldebug.c |
| @@ -824,8 +824,11 @@ l_noret luaG_runerror (lua_State *L, con |
| va_start(argp, fmt); |
| msg = luaO_pushvfstring(L, fmt, argp); /* format message */ |
| va_end(argp); |
| - if (isLua(ci)) /* if Lua function, add source:line information */ |
| + if (isLua(ci)) { /* if Lua function, add source:line information */ |
| luaG_addinfo(L, msg, ci_func(ci)->p->source, getcurrentline(ci)); |
| + setobjs2s(L, L->top - 2, L->top - 1); /* remove 'msg' from the stack */ |
| + L->top--; |
| + } |
| luaG_errormsg(L); |
| } |
| |
| --- a/src/lvm.c |
| +++ b/src/lvm.c |
| @@ -656,8 +656,10 @@ void luaV_concat (lua_State *L, int tota |
| /* collect total length and number of strings */ |
| for (n = 1; n < total && tostring(L, s2v(top - n - 1)); n++) { |
| size_t l = vslen(s2v(top - n - 1)); |
| - if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl)) |
| + if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl)) { |
| + L->top = top - total; /* pop strings to avoid wasting stack */ |
| luaG_runerror(L, "string length overflow"); |
| + } |
| tl += l; |
| } |
| if (tl <= LUAI_MAXSHORTLEN) { /* is result a short string? */ |
| @@ -672,7 +674,7 @@ void luaV_concat (lua_State *L, int tota |
| setsvalue2s(L, top - n, ts); /* create result */ |
| } |
| total -= n-1; /* got 'n' strings to create 1 new */ |
| - L->top -= n-1; /* popped 'n' strings and pushed one */ |
| + L->top = top - (n - 1); /* popped 'n' strings and pushed one */ |
| } while (total > 1); /* repeat until only 1 result left */ |
| } |
| |