Limit ASN.1 structure sizes to 256K. Prevent some allocation size overflows.

See CRL-01-006.

lib/vauth/cleartext.c

@@ -66,16 +66,27 @@ CURLcode Curl_auth_create_plain_message(struct Curl_easy *data,
   char *plainauth;
   size_t ulen;
   size_t plen;
+  size_t plainlen;
 
+  *outlen = 0;
+  *outptr = NULL;
   ulen = strlen(userp);
   plen = strlen(passwdp);
 
-  plainauth = malloc(2 * ulen + plen + 2);
-  if(!plainauth) {
-    *outlen = 0;
-    *outptr = NULL;
+  /* Compute binary message length, checking for overflows. */
+  plainlen = 2 * ulen;
+  if(plainlen < ulen)
+    return CURLE_OUT_OF_MEMORY;
+  plainlen += plen;
+  if(plainlen < plen)
+    return CURLE_OUT_OF_MEMORY;
+  plainlen += 2;
+  if(plainlen < 2)
+    return CURLE_OUT_OF_MEMORY;
+
+  plainauth = malloc(plainlen);
+  if(!plainauth)
     return CURLE_OUT_OF_MEMORY;
-  }
 
   /* Calculate the reply */
   memcpy(plainauth, userp, ulen);
@@ -85,8 +96,7 @@ CURLcode Curl_auth_create_plain_message(struct Curl_easy *data,
   memcpy(plainauth + 2 * ulen + 2, passwdp, plen);
 
   /* Base64 encode the reply */
-  result = Curl_base64_encode(data, plainauth, 2 * ulen + plen + 2, outptr,
-                              outlen);
+  result = Curl_base64_encode(data, plainauth, plainlen, outptr, outlen);
   free(plainauth);
 
   return result;

lib/vtls/cyassl.c

@@ -512,7 +512,8 @@ cyassl_connect_step2(struct connectdata *conn,
     }
 
     memset(&x509_parsed, 0, sizeof x509_parsed);
-    Curl_parseX509(&x509_parsed, x509_der, x509_der + x509_der_len);
+    if(Curl_parseX509(&x509_parsed, x509_der, x509_der + x509_der_len))
+      return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
 
     pubkey = &x509_parsed.subjectPublicKeyInfo;
     if(!pubkey->header || pubkey->end <= pubkey->header) {

lib/vtls/gskit.c

@@ -875,9 +875,8 @@ static CURLcode gskit_connect_step3(struct connectdata *conn, int sockindex)
     curl_X509certificate x509;
     curl_asn1Element *p;
 
-    if(!cert)
+    if(Curl_parseX509(&x509, cert, certend))
       return CURLE_SSL_PINNEDPUBKEYNOTMATCH;
-    Curl_parseX509(&x509, cert, certend);
     p = &x509.subjectPublicKeyInfo;
     result = Curl_pin_peer_pubkey(data, ptr, p->header, p->end - p->header);
     if(result) {

lib/x509asn1.c

@@ -40,6 +40,9 @@
 #include "curl_memory.h"
 #include "memdebug.h"
 
+/* For overflow checks. */
+#define CURL_SIZE_T_MAX         ((size_t) ~0)
+
 
 /* ASN.1 OIDs. */
 static const char       cnOID[] = "2.5.4.3";    /* Common name. */
@@ -117,7 +120,7 @@ const char * Curl_getASN1Element(curl_asn1Element * elem,
      Returns a pointer in source string after the parsed element, or NULL
      if an error occurs. */
 
-  if(beg >= end || !*beg)
+  if(!beg || !end || (size_t) (end - beg) > CURL_ASN1_MAX)
     return (const char *) NULL;
 
   /* Process header byte. */
@@ -198,15 +201,17 @@ static const char * bool2str(const char * beg, const char * end)
 static const char * octet2str(const char * beg, const char * end)
 {
   size_t n = end - beg;
-  char * buf;
+  char * buf = NULL;
 
   /* Convert an ASN.1 octet string to a printable string.
      Return the dynamically allocated string, or NULL if an error occurs. */
 
+  if(n <= (CURL_SIZE_T_MAX - 1) / 3) {
     buf = malloc(3 * n + 1);
     if(buf)
       for(n = 0; beg < end; n += 3)
         snprintf(buf + n, 4, "%02x:", *(const unsigned char *) beg++);
+  }
   return buf;
 }
 
@@ -282,6 +287,8 @@ utf8asn1str(char * * to, int type, const char * from, const char * end)
 
   if(inlength % size)
     return -1;  /* Length inconsistent with character size. */
+  if(inlength / size > (CURL_SIZE_T_MAX - 1) / 4)
+    return -1;  /* Too big. */
   buf = malloc(4 * (inlength / size) + 1);
   if(!buf)
     return -1;  /* Not enough memory. */
@@ -669,7 +676,7 @@ const char * Curl_DNtostr(curl_asn1Element * dn)
  * X509 parser.
  */
 
-void Curl_parseX509(curl_X509certificate * cert,
+int Curl_parseX509(curl_X509certificate * cert,
                    const char * beg, const char * end)
 {
   curl_asn1Element elem;
@@ -686,7 +693,8 @@ void Curl_parseX509(curl_X509certificate * cert,
   cert->certificate.end = end;
 
   /* Get the sequence content. */
-  Curl_getASN1Element(&elem, beg, end);
+  if(!Curl_getASN1Element(&elem, beg, end))
+    return -1;  /* Invalid bounds/size. */
   beg = elem.beg;
   end = elem.end;
 
@@ -749,6 +757,7 @@ void Curl_parseX509(curl_X509certificate * cert,
   }
   if(elem.tag == 3)
     Curl_getASN1Element(&cert->extensions, elem.beg, elem.end);
+  return 0;
 }
 
 static size_t copySubstring(char * to, const char * from)
@@ -889,7 +898,8 @@ CURLcode Curl_extract_certinfo(struct connectdata * conn,
   /* Prepare the certificate information for curl_easy_getinfo(). */
 
   /* Extract the certificate ASN.1 elements. */
-  Curl_parseX509(&cert, beg, end);
+  if(Curl_parseX509(&cert, beg, end))
+    return CURLE_OUT_OF_MEMORY;
 
   /* Subject. */
   ccp = Curl_DNtostr(&cert.subject);
@@ -1080,9 +1090,8 @@ CURLcode Curl_verifyhost(struct connectdata * conn,
   if(!data->set.ssl.verifyhost)
     return CURLE_OK;
 
-  if(!beg)
+  if(Curl_parseX509(&cert, beg, end))
     return CURLE_PEER_FAILED_VERIFICATION;
-  Curl_parseX509(&cert, beg, end);
 
   /* Get the server IP address. */
 #ifdef ENABLE_IPV6

lib/x509asn1.h

@@ -8,7 +8,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -34,6 +34,9 @@
  * Constants.
  */
 
+/* Largest supported ASN.1 structure. */
+#define CURL_ASN1_MAX                   ((size_t) 0x40000)      /* 256K */
+
 /* ASN.1 classes. */
 #define CURL_ASN1_UNIVERSAL             0
 #define CURL_ASN1_APPLICATION           1
@@ -121,7 +124,7 @@ const char * Curl_getASN1Element(curl_asn1Element * elem,
                                  const char * beg, const char * end);
 const char * Curl_ASN1tostr(curl_asn1Element * elem, int type);
 const char * Curl_DNtostr(curl_asn1Element * dn);
-void Curl_parseX509(curl_X509certificate * cert,
+int Curl_parseX509(curl_X509certificate * cert,
                    const char * beg, const char * end);
 CURLcode Curl_extract_certinfo(struct connectdata * conn, int certnum,
                                const char * beg, const char * end);