* Crosscheck the length of the body chunk with the length of the ajp message

  to prevent readings beyond the buffer boundaries which possibly could reveal
  sensitive memory contents to the client.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@383339 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index 391777e5d58a6a9300ed283efad5d3f2c676114e..1bbfd55bf3ee727786efcb0bdad91d3ccc6fd528 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -2,6 +2,11 @@
 Changes with Apache 2.3.0
   [Remove entries to the current 2.0 and 2.2 section below, when backported]
 
+  *) mod_proxy_ajp: Crosscheck the length of the body chunk with the length of
+     the ajp message to prevent mod_proxy_ajp from reading beyond the buffer
+     boundaries and thus revealing possibly sensitive memory contents to the
+     client. [Ruediger Pluem]
+
   *) mod_proxy_http: Do send keep-alive header if the client sent
      connection: keep-alive and do not close backend connection if the client
      sent connection: close. PR 38524. [Ruediger Pluem, Joe Orton]

diff --git a/modules/proxy/ajp_header.c b/modules/proxy/ajp_header.c
index 03bfec4e04f8c432a5cdf8a0ae8372c2751023df..07a9f3293dd30989736dad5ede59dfb24cf92e26 100644 (file)
--- a/modules/proxy/ajp_header.c
+++ b/modules/proxy/ajp_header.c
@@ -683,6 +683,7 @@ apr_status_t  ajp_parse_data(request_rec  *r, ajp_msg_t *msg,
 {
     apr_byte_t result;
     apr_status_t rc;
+    apr_uint16_t expected_len;
 
     rc = ajp_msg_get_uint8(msg, &result);
     if (rc != APR_SUCCESS) {
@@ -699,6 +700,23 @@ apr_status_t  ajp_parse_data(request_rec  *r, ajp_msg_t *msg,
     if (rc != APR_SUCCESS) {
         return rc;
     }
+    /*
+     * msg->len contains the complete length of the message including all
+     * headers. So the expected length for a CMD_AJP13_SEND_BODY_CHUNK is
+     * msg->len minus the sum of
+     * AJP_HEADER_LEN    : The length of the header to every AJP message.
+     * AJP_HEADER_SZ_LEN : The header giving the size of the chunk.
+     * 1                 : The CMD_AJP13_SEND_BODY_CHUNK indicator byte (0x03).
+     * 1                 : The last byte of this message always seems to be
+     *                     0x00 and is not part of the chunk.
+     */
+    expected_len = msg->len - (AJP_HEADER_LEN + AJP_HEADER_SZ_LEN + 1 + 1);
+    if (*len != expected_len) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
+               "ajp_parse_data: Wrong chunk length. Length of chunk is %i,"
+               " expected length is %i.", *len, expected_len);
+        return AJP_EBAD_HEADER;
+    }
     *ptr = (char *)&(msg->buf[msg->pos]);
     return APR_SUCCESS;
 }