[src/trunk]: src/external/mit/lua/dist/src lua: apply upstream bugfix for "Lu...

[nikita <nikita%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f3d5ad5cb6ce
branches:  trunk
changeset: 374297:f3d5ad5cb6ce
user:      nikita <nikita%NetBSD.org@localhost>
date:      Mon Apr 17 19:35:36 2023 +0000

description:
lua: apply upstream bugfix for "Lua-stack overflow when C stack overflows while
handling an error." (CVE-2022-33099)

 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".

diffstat:

 external/mit/lua/dist/src/ldebug.c |  7 +++++--
 external/mit/lua/dist/src/lvm.c    |  8 +++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diffs (52 lines):

diff -r 688f67a00f60 -r f3d5ad5cb6ce external/mit/lua/dist/src/ldebug.c
--- a/external/mit/lua/dist/src/ldebug.c        Mon Apr 17 19:19:00 2023 +0000
+++ b/external/mit/lua/dist/src/ldebug.c        Mon Apr 17 19:35:36 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ldebug.c,v 1.12 2023/04/16 20:46:17 nikita Exp $       */
+/*     $NetBSD: ldebug.c,v 1.13 2023/04/17 19:35:36 nikita Exp $       */
 
 /*
 ** Id: ldebug.c 
@@ -828,8 +828,11 @@ 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);
 }
 
diff -r 688f67a00f60 -r f3d5ad5cb6ce external/mit/lua/dist/src/lvm.c
--- a/external/mit/lua/dist/src/lvm.c   Mon Apr 17 19:19:00 2023 +0000
+++ b/external/mit/lua/dist/src/lvm.c   Mon Apr 17 19:35:36 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: lvm.c,v 1.15 2023/04/16 20:46:17 nikita Exp $  */
+/*     $NetBSD: lvm.c,v 1.16 2023/04/17 19:35:36 nikita Exp $  */
 
 /*
 ** Id: lvm.c 
@@ -698,8 +698,10 @@ 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? */
@@ -714,7 +716,7 @@ 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 */
 }