From 33f7a2ac3bff0b73cfae18f1070253e49faa97b0 Mon Sep 17 00:00:00 2001
From: Jim Jagielski <jim@apache.org>
Date: Tue, 10 Jun 2008 15:30:00 +0000
Subject: [PATCH] Patch for CVE-2008-2364...

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@666154 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES                        |  6 ++++++
 modules/proxy/mod_proxy_http.c | 33 ++++++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/CHANGES b/CHANGES
index 8b07da76d5..9dccaf348d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2,6 +2,12 @@
 Changes with Apache 2.3.0
 [ When backported to 2.2.x, remove entry from this file ]
 
+  *) SECURITY: CVE-2008-2364 (cve.mitre.org)
+     mod_proxy_http: Better handling of excessive interim responses
+     from origin server to prevent potential denial of service and high
+     memory usage. Reported by Ryujiro Shibuya. [Ruediger Pluem,
+     Joe Orton, Jim Jagielski]
+
   *) mod_proxy_http: Do not forward requests with 'Expect: 100-continue' to
      known HTTP/1.0 servers. Return 'Expectation failed' (417) instead.
      [Ruediger Pluem]
diff --git a/modules/proxy/mod_proxy_http.c b/modules/proxy/mod_proxy_http.c
index 8e7e40b219..012e1a9f0f 100644
--- a/modules/proxy/mod_proxy_http.c
+++ b/modules/proxy/mod_proxy_http.c
@@ -1312,6 +1312,16 @@ apr_status_t ap_proxygetline(apr_bucket_brigade *bb, char *s, int n, request_rec
     return rv;
 }
 
+/*
+ * Limit the number of interim respones we sent back to the client. Otherwise
+ * we suffer from a memory build up. Besides there is NO sense in sending back
+ * an unlimited number of interim responses to the client. Thus if we cross
+ * this limit send back a 502 (Bad Gateway).
+ */
+#ifndef AP_MAX_INTERIM_RESPONSES
+#define AP_MAX_INTERIM_RESPONSES 10
+#endif
+
 static
 apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
                                             proxy_conn_rec *backend,
@@ -1326,8 +1336,8 @@ apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
     apr_bucket *e;
     apr_bucket_brigade *bb, *tmp_bb;
     int len, backasswards;
-    int interim_response; /* non-zero whilst interim 1xx responses
-                           * are being read. */
+    int interim_response = 0; /* non-zero whilst interim 1xx responses
+                               * are being read. */
     int pread_len = 0;
     apr_table_t *save_table;
     int backend_broke = 0;
@@ -1343,6 +1353,7 @@ apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
      */
 
     rp = ap_proxy_make_fake_req(origin, r);
+    ap_proxy_pre_http_request(origin, rp);
     /* In case anyone needs to know, this is a fake request that is really a
      * response.
      */
@@ -1528,7 +1539,6 @@ apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
             if ((buf = apr_table_get(r->headers_out, "Content-Type"))) {
                 ap_set_content_type(r, apr_pstrdup(p, buf));
             }
-            ap_proxy_pre_http_request(origin,rp);
 
             /* Clear hop-by-hop headers */
             for (i=0; hop_by_hop_hdrs[i]; ++i) {
@@ -1577,7 +1587,12 @@ apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
             backend->close += 1;
         }
 
-        interim_response = ap_is_HTTP_INFO(r->status);
+        if (ap_is_HTTP_INFO(r->status)) {
+            interim_response++;
+        }
+        else {
+            interim_response = 0;
+        }
         if (interim_response) {
             /* RFC2616 tells us to forward this.
              *
@@ -1778,7 +1793,15 @@ apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
 
             apr_brigade_cleanup(bb);
         }
-    } while (interim_response);
+    } while (interim_response && (interim_response < AP_MAX_INTERIM_RESPONSES));
+
+    /* See define of AP_MAX_INTERIM_RESPONSES for why */
+    if (interim_response >= AP_MAX_INTERIM_RESPONSES) {
+        return ap_proxyerror(r, HTTP_BAD_GATEWAY,
+                             apr_psprintf(p, 
+                             "Too many (%d) interim responses from origin server",
+                             interim_response));
+    }
 
     /* If our connection with the client is to be aborted, return DONE. */
     if (c->aborted || backend_broke) {
-- 
2.40.0