[or-cvs] Be more proactive about noticing underflows: size_t values ...

[Nick Mathewson]

Update of /home/or/cvsroot/tor/src/common
In directory moria.mit.edu:/tmp/cvs-serv28436/src/common

Modified Files:
	compat.c crypto.c torint.h util.c 
Log Message:
Be more proactive about noticing underflows: size_t values greater than 0x800...00 are likely to be trouble.

Index: compat.c
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/compat.c,v
retrieving revision 1.20
retrieving revision 1.21
diff -u -d -r1.20 -r1.21
--- compat.c	1 Dec 2004 03:51:59 -0000	1.20
+++ compat.c	2 Dec 2004 04:33:01 -0000	1.21
@@ -100,6 +100,8 @@
   int r;
   if (size == 0)
     return -1; /* no place for the NUL */
+  if (size > SIZE_T_CEILING)
+    return -1;
 #ifdef MS_WINDOWS
   r = _vsnprintf(str, size, format, args);
 #else

Index: crypto.c
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/crypto.c,v
retrieving revision 1.126
retrieving revision 1.127
diff -u -d -r1.126 -r1.127
--- crypto.c	1 Dec 2004 03:48:12 -0000	1.126
+++ crypto.c	2 Dec 2004 04:33:01 -0000	1.127
@@ -1520,6 +1520,8 @@
   */
   if (destlen < ((srclen/48)+1)*66)
     return -1;
+  if (destlen > SIZE_T_CEILING)
+    return -1;
 
   EVP_EncodeInit(&ctx);
   EVP_EncodeUpdate(&ctx, dest, &len, (char*) src, srclen);
@@ -1543,6 +1545,8 @@
   */
   if (destlen < ((srclen/64)+1)*49)
     return -1;
+  if (destlen > SIZE_T_CEILING)
+    return -1;
 
   EVP_DecodeInit(&ctx);
   EVP_DecodeUpdate(&ctx, dest, &len, (char*) src, srclen);
@@ -1562,6 +1566,7 @@
 
   tor_assert((nbits%5) == 0); /* We need an even multiple of 5 bits. */
   tor_assert((nbits/5)+1 <= destlen); /* We need enough space. */
+  tor_assert(destlen < SIZE_T_CEILING);
 
   for (i=0,bit=0; bit < nbits; ++i, bit+=5) {
     /* set v to the 16-bit value starting at src[bits/8], 0-padded. */
@@ -1588,6 +1593,7 @@
   uint8_t c;
   size_t count;
   char *tmp;
+  tor_assert(key_out_len < SIZE_T_CEILING);
 
 #define EXPBIAS 6
   c = s2k_specifier[8];

Index: torint.h
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/torint.h,v
retrieving revision 1.14
retrieving revision 1.15
diff -u -d -r1.14 -r1.15
--- torint.h	29 Nov 2004 22:25:28 -0000	1.14
+++ torint.h	2 Dec 2004 04:33:01 -0000	1.15
@@ -232,5 +232,8 @@
 #endif
 #endif
 
+/* Any size_t larger than this amount is likely to be an underflow. */
+#define SIZE_T_CEILING (1u<<(sizeof(size_t)*8 - 1))
+
 #endif /* __TORINT_H */
 

Index: util.c
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/util.c,v
retrieving revision 1.192
retrieving revision 1.193
diff -u -d -r1.192 -r1.193
--- util.c	1 Dec 2004 03:48:12 -0000	1.192
+++ util.c	2 Dec 2004 04:33:01 -0000	1.193
@@ -18,6 +18,7 @@
 #include "util.h"
 #include "log.h"
 #include "crypto.h"
+#include "torint.h"
 
 #ifdef MS_WINDOWS
 #include <io.h>
@@ -218,6 +219,8 @@
   tor_assert(s);
   tor_assert(insert);
   tor_assert(n > 0);
+  tor_assert(n < SIZE_T_CEILING);
+  tor_assert(dest_len < SIZE_T_CEILING);
   len_in = strlen(s);
   len_ins = strlen(insert);
   len_out = len_in + (len_in/n)*len_ins;
@@ -444,6 +447,7 @@
   char *cp;
 
   tor_assert(destlen >= srclen*2+1);
+  tor_assert(destlen < SIZE_T_CEILING);
 
   cp = dest;
   end = src+srclen;
@@ -477,7 +481,7 @@
   int v1,v2;
   if ((srclen % 2) != 0)
     return -1;
-  if (destlen < srclen/2)
+  if (destlen < srclen/2 || destlen > SIZE_T_CEILING)
     return -1;
   end = src+srclen;
   while (src<end) {
@@ -703,6 +707,9 @@
   size_t numread = 0;
   int result;
 
+  if (count > SIZE_T_CEILING)
+    return -1;
+
   while (numread != count) {
     if (isSocket)
       result = recv(fd, buf+numread, count-numread, 0);