lua

commit 5853c37a83ec66ccb45094f9aeac23dfdbcde671
parent 842a83f09caa2ebd4bc03e0076420148ac07c808
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Thu, 21 Dec 2023 13:37:24 -0300

Bug: Buffer overflow in string concatenation

Even if the string fits in size_t, the whole size of the TString object
can overflow when we add the header.

Diffstat:
M
lstring.c
 | 
2
+-
M
lvm.c
 | 
2
+-

2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/lstring.c b/lstring.c
@@ -224,7 +224,7 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
     return internshrstr(L, str, l);
   else {
     TString *ts;
-    if (l_unlikely(l >= (MAX_SIZE - sizeof(TString))/sizeof(char)))
+    if (l_unlikely(l * sizeof(char) >= (MAX_SIZE - sizeof(TString))))
       luaM_toobig(L);
     ts = luaS_createlngstrobj(L, l);
     memcpy(getlngstr(ts), str, l * sizeof(char));
diff --git a/lvm.c b/lvm.c
@@ -661,7 +661,7 @@ void luaV_concat (lua_State *L, int total) {
       /* collect total length and number of strings */
       for (n = 1; n < total && tostring(L, s2v(top - n - 1)); n++) {
         size_t l = tsslen(tsvalue(s2v(top - n - 1)));
-        if (l_unlikely(l >= (MAX_SIZE/sizeof(char)) - tl)) {
+        if (l_unlikely(l >= MAX_SIZE - sizeof(TString) - tl)) {
           L->top.p = top - total;  /* pop strings to avoid wasting stack */
           luaG_runerror(L, "string length overflow");
         }