curl_easy_duphandle: CURLOPT_COPYPOSTFIELDS read out of bounds

When duplicating a handle, the data to post was duplicated using
strdup() when it could be binary and contain zeroes and it was not even
zero terminated! This caused read out of bounds crashes/segfaults.

Since the lib/strdup.c file no longer is easily shared with the curl
tool with this change, it now uses its own version instead.

Bug: http://curl.haxx.se/docs/adv_20141105.html
CVE: CVE-2014-3707
Reported-By: Symeon Paraschoudis

5 files changed, 64 insertions, 56 deletions

diff --git a/lib/formdata.c b/lib/formdata.c
index 1abfbc42b..73d3b6d72 100644
--- a/lib/formdata.c
+++ b/lib/formdata.c
@@ -36,6 +36,7 @@
 #include "strequal.h"
 #include "curl_memory.h"
 #include "sendf.h"
+#include "strdup.h"
 
 #define _MPRINTF_REPLACE /* use our functions only */
 #include <curl/mprintf.h>
@@ -210,46 +211,6 @@ static const char *ContentTypeForFilename(const char *filename,
 
 /***************************************************************************
  *
- * memdup()
- *
- * Copies the 'source' data to a newly allocated buffer buffer (that is
- * returned). Uses buffer_length if not null, else uses strlen to determine
- * the length of the buffer to be copied
- *
- * Returns the new pointer or NULL on failure.
- *
- ***************************************************************************/
-static char *memdup(const char *src, size_t buffer_length)
-{
-  size_t length;
-  bool add = FALSE;
-  char *buffer;
-
-  if(buffer_length)
-    length = buffer_length;
-  else if(src) {
-    length = strlen(src);
-    add = TRUE;
-  }
-  else
-    /* no length and a NULL src pointer! */
-    return strdup("");
-
-  buffer = malloc(length+add);
-  if(!buffer)
-    return NULL; /* fail */
-
-  memcpy(buffer, src, length);
-
-  /* if length unknown do null termination */
-  if(add)
-    buffer[length] = '\0';
-
-  return buffer;
-}
-
-/***************************************************************************
- *
  * FormAdd()
  *
  * Stores a formpost parameter and builds the appropriate linked list.
@@ -678,9 +639,12 @@ CURLFORMcode FormAdd(struct curl_httppost **httppost,
            (form == first_form) ) {
           /* Note that there's small risk that form->name is NULL here if the
              app passed in a bad combo, so we better check for that first. */
-          if(form->name)
+          if(form->name) {
             /* copy name (without strdup; possibly contains null characters) */
-            form->name = memdup(form->name, form->namelength);
+            form->name = Curl_memdup(form->name, form->namelength?
+                                     form->namelength:
+                                     strlen(form->name)+1);
+          }
           if(!form->name) {
             return_value = CURL_FORMADD_MEMORY;
             break;
@@ -691,7 +655,9 @@ CURLFORMcode FormAdd(struct curl_httppost **httppost,
                             HTTPPOST_PTRCONTENTS | HTTPPOST_PTRBUFFER |
                             HTTPPOST_CALLBACK)) && form->value) {
           /* copy value (without strdup; possibly contains null characters) */
-          form->value = memdup(form->value, form->contentslength);
+          form->value = Curl_memdup(form->value, form->contentslength?
+                                    form->contentslength:
+                                    strlen(form->value)+1);
           if(!form->value) {
             return_value = CURL_FORMADD_MEMORY;
             break;
diff --git a/lib/strdup.c b/lib/strdup.c
index 3b776b184..4b5bd4042 100644
--- a/lib/strdup.c
+++ b/lib/strdup.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2014, 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
@@ -19,12 +19,12 @@
  * KIND, either express or implied.
  *
  ***************************************************************************/
-/*
- * This file is 'mem-include-scan' clean. See test 1132.
- */
 #include "curl_setup.h"
-
 #include "strdup.h"
+#include "curl_memory.h"
+
+/* The last #include file should be: */
+#include "memdebug.h"
 
 #ifndef HAVE_STRDUP
 char *curlx_strdup(const char *str)
@@ -50,3 +50,25 @@ char *curlx_strdup(const char *str)
 
 }
 #endif
+
+/***************************************************************************
+ *
+ * Curl_memdup(source, length)
+ *
+ * Copies the 'source' data to a newly allocated buffer (that is
+ * returned). Copies 'length' bytes.
+ *
+ * Returns the new pointer or NULL on failure.
+ *
+ ***************************************************************************/
+char *Curl_memdup(const char *src, size_t length)
+{
+  char *buffer = malloc(length);
+  if(!buffer)
+    return NULL; /* fail */
+
+  memcpy(buffer, src, length);
+
+  /* if length unknown do null termination */
+  return buffer;
+}
diff --git a/lib/strdup.h b/lib/strdup.h
index 49af9117e..23a71f863 100644
--- a/lib/strdup.h
+++ b/lib/strdup.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2010, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2014, 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
@@ -26,5 +26,6 @@
 #ifndef HAVE_STRDUP
 extern char *curlx_strdup(const char *str);
 #endif
+char *Curl_memdup(const char *src, size_t buffer_length);
 
 #endif /* HEADER_CURL_STRDUP_H */
diff --git a/lib/url.c b/lib/url.c
index 4974a1af4..40d4fed59 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -125,6 +125,7 @@ int curl_win32_idn_to_ascii(const char *in, char **out);
 #include "multihandle.h"
 #include "pipeline.h"
 #include "dotdot.h"
+#include "strdup.h"
 
 #define _MPRINTF_REPLACE /* use our functions only */
 #include <curl/mprintf.h>
@@ -270,8 +271,9 @@ void Curl_freeset(struct SessionHandle *data)
 {
   /* Free all dynamic strings stored in the data->set substructure. */
   enum dupstring i;
-  for(i=(enum dupstring)0; i < STRING_LAST; i++)
+  for(i=(enum dupstring)0; i < STRING_LAST; i++) {
     Curl_safefree(data->set.str[i]);
+  }
 
   if(data->change.referer_alloc) {
     Curl_safefree(data->change.referer);
@@ -356,14 +358,24 @@ CURLcode Curl_dupset(struct SessionHandle *dst, struct SessionHandle *src)
   memset(dst->set.str, 0, STRING_LAST * sizeof(char *));
 
   /* duplicate all strings */
-  for(i=(enum dupstring)0; i< STRING_LAST; i++) {
+  for(i=(enum dupstring)0; i< STRING_LASTZEROTERMINATED; i++) {
     result = setstropt(&dst->set.str[i], src->set.str[i]);
     if(result)
-      break;
+      return result;
   }
 
-  /* If a failure occurred, freeing has to be performed externally. */
-  return result;
+  /* duplicate memory areas pointed to */
+  i = STRING_COPYPOSTFIELDS;
+  if(src->set.postfieldsize && src->set.str[i]) {
+    /* postfieldsize is curl_off_t, Curl_memdup() takes a size_t ... */
+    dst->set.str[i] = Curl_memdup(src->set.str[i], src->set.postfieldsize);
+    if(!dst->set.str[i])
+      return CURLE_OUT_OF_MEMORY;
+    /* point to the new copy */
+    dst->set.postfields = dst->set.str[i];
+  }
+
+  return CURLE_OK;
 }
 
 /*
diff --git a/lib/urldata.h b/lib/urldata.h
index 5a65c4a74..62a2b8048 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1372,7 +1372,6 @@ enum dupstring {
   STRING_KRB_LEVEL,       /* krb security level */
   STRING_NETRC_FILE,      /* if not NULL, use this instead of trying to find
                              $HOME/.netrc */
-  STRING_COPYPOSTFIELDS,  /* if POST, set the fields' values here */
   STRING_PROXY,           /* proxy to use */
   STRING_SET_RANGE,       /* range, if used */
   STRING_SET_REFERER,     /* custom string for the HTTP referer field */
@@ -1415,7 +1414,15 @@ enum dupstring {
 
   STRING_BEARER,          /* <bearer>, if used */
 
-  /* -- end of strings -- */
+  /* -- end of zero-terminated strings -- */
+
+  STRING_LASTZEROTERMINATED,
+
+  /* -- below this are pointers to binary data that cannot be strdup'ed.
+     Each such pointer must be added manually to Curl_dupset() --- */
+
+  STRING_COPYPOSTFIELDS,  /* if POST, set the fields' values here */
+
   STRING_LAST /* not used, just an end-of-list marker */
 };