SECURITY: CVE-2016-8740

mod_http2: properly crafted, endless HTTP/2 CONTINUATION frames could be used to exhaust all server's memory.

Reported by: Naveen Tiwari <naveen.tiwari@asu.edu> and CDF/SEFCOM at Arizona State University



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1772576 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 33 insertions, 28 deletions

diff --git a/modules/http2/h2_stream.c b/modules/http2/h2_stream.c
index 2d179d0b0f..d31193909c 100644
--- a/modules/http2/h2_stream.c
+++ b/modules/http2/h2_stream.c
@@ -333,45 +333,50 @@ apr_status_t h2_stream_add_header(h2_stream *stream,
                                   const char *name, size_t nlen,
                                   const char *value, size_t vlen)
 {
+    int error = 0;
     ap_assert(stream);
     
-    if (!stream->has_response) {
-        if (name[0] == ':') {
-            if ((vlen) > stream->session->s->limit_req_line) {
-                /* pseudo header: approximation of request line size check */
-                ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, stream->session->c,
-                              "h2_stream(%ld-%d): pseudo header %s too long", 
-                              stream->session->id, stream->id, name);
-                return h2_stream_set_error(stream, 
-                                           HTTP_REQUEST_URI_TOO_LARGE);
-            }
-        }
-        else if ((nlen + 2 + vlen) > stream->session->s->limit_req_fieldsize) {
-            /* header too long */
+    if (stream->has_response) {
+        return APR_EINVAL;    
+    }
+    ++stream->request_headers_added;
+    if (name[0] == ':') {
+        if ((vlen) > stream->session->s->limit_req_line) {
+            /* pseudo header: approximation of request line size check */
             ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, stream->session->c,
-                          "h2_stream(%ld-%d): header %s too long", 
+                          "h2_stream(%ld-%d): pseudo header %s too long", 
                           stream->session->id, stream->id, name);
-            return h2_stream_set_error(stream, 
-                                       HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE);
+            error = HTTP_REQUEST_URI_TOO_LARGE;
         }
-        
-        if (name[0] != ':') {
-            ++stream->request_headers_added;
-            if (stream->request_headers_added 
-                > stream->session->s->limit_req_fields) {
-                /* too many header lines */
-                ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, stream->session->c,
-                              "h2_stream(%ld-%d): too many header lines", 
-                              stream->session->id, stream->id);
-                return h2_stream_set_error(stream, 
-                                           HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE);
-            }
+    }
+    else if ((nlen + 2 + vlen) > stream->session->s->limit_req_fieldsize) {
+        /* header too long */
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, stream->session->c,
+                      "h2_stream(%ld-%d): header %s too long", 
+                      stream->session->id, stream->id, name);
+        error = HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE;
+    }
+    
+    if (stream->request_headers_added 
+        > stream->session->s->limit_req_fields + 4) {
+        /* too many header lines, include 4 pseudo headers */
+        if (stream->request_headers_added 
+            > stream->session->s->limit_req_fields + 4 + 100) {
+            /* yeah, right */
+            return APR_ECONNRESET;
         }
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, stream->session->c,
+                      "h2_stream(%ld-%d): too many header lines", 
+                      stream->session->id, stream->id);
+        error = HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE;
     }
     
     if (h2_stream_is_scheduled(stream)) {
         return add_trailer(stream, name, nlen, value, vlen);
     }
+    else if (error) {
+        return h2_stream_set_error(stream, error); 
+    }
     else {
         if (!stream->rtmp) {
             stream->rtmp = h2_req_create(stream->id, stream->pool,