From 29c63b786ae028d82405421585e91283c8fa0da3 Mon Sep 17 00:00:00 2001 From: Stefan Eissing Date: Sun, 4 Dec 2016 22:06:30 +0000 Subject: [PATCH] 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 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 --- CHANGES | 4 +++ modules/http2/h2_session.c | 11 +++++-- modules/http2/h2_stream.c | 61 +++++++++++++++++++++----------------- 3 files changed, 46 insertions(+), 30 deletions(-) diff --git a/CHANGES b/CHANGES index bb840c0edde..bb92454986f 100644 --- a/CHANGES +++ b/CHANGES @@ -1,6 +1,10 @@ -*- coding: utf-8 -*- Changes with Apache 2.5.0 + *) mod_http2: CVE-2016-8740: Mitigate DoS memory exhaustion via endless + CONTINUATION frames. + [Naveen Tiwari and CDF/SEFCOM at Arizona State University, Stefan Eissing] + *) mod_lua: Fix default value of LuaInherit directive. It should be 'parent-first' instead of 'none', as per documentation. PR 60419 [Christophe Jaillet] diff --git a/modules/http2/h2_session.c b/modules/http2/h2_session.c index 0a29a3b18cc..44eed633256 100644 --- a/modules/http2/h2_session.c +++ b/modules/http2/h2_session.c @@ -394,7 +394,7 @@ static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame, (void)flags; stream = get_stream(session, frame->hd.stream_id); if (!stream) { - ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c, + ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c, APLOGNO(02920) "h2_session: stream(%ld-%d): on_header unknown stream", session->id, (int)frame->hd.stream_id); @@ -403,7 +403,14 @@ static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame, status = h2_stream_add_header(stream, (const char *)name, namelen, (const char *)value, valuelen); - if (status != APR_SUCCESS && !h2_stream_is_ready(stream)) { + if (status == APR_ECONNRESET) { + ap_log_cerror(APLOG_MARK, APLOG_TRACE1, status, session->c, + "h2-stream(%ld-%d): on_header, reset stream", + session->id, stream->id); + nghttp2_submit_rst_stream(ngh2, NGHTTP2_FLAG_NONE, stream->id, + NGHTTP2_INTERNAL_ERROR); + } + else if (status != APR_SUCCESS && !h2_stream_is_ready(stream)) { return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE; } return 0; diff --git a/modules/http2/h2_stream.c b/modules/http2/h2_stream.c index 2d179d0b0fc..d31193909c7 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,