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[nginx] HTTP/2: limited number of DATA frames.

Maxim Dounin
August 13, 2019 01:02PM
details: https://hg.nginx.org/nginx/rev/99257b06b0bd
branches:
changeset: 7548:99257b06b0bd
user: Ruslan Ermilov <ru@nginx.com>
date: Tue Aug 13 15:43:36 2019 +0300
description:
HTTP/2: limited number of DATA frames.

Fixed excessive memory growth and CPU usage if stream windows are
manipulated in a way that results in generating many small DATA frames.
Fix is to limit the number of simultaneously allocated DATA frames.

diffstat:

src/http/v2/ngx_http_v2.c | 2 ++
src/http/v2/ngx_http_v2.h | 2 ++
src/http/v2/ngx_http_v2_filter_module.c | 22 +++++++++++++++++-----
3 files changed, 21 insertions(+), 5 deletions(-)

diffs (67 lines):

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -4369,6 +4369,8 @@ ngx_http_v2_close_stream(ngx_http_v2_str
*/
pool = stream->pool;

+ h2c->frames -= stream->frames;
+
ngx_http_free_request(stream->request, rc);

if (pool != h2c->state.pool) {
diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h
--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -192,6 +192,8 @@ struct ngx_http_v2_stream_s {

ngx_buf_t *preread;

+ ngx_uint_t frames;
+
ngx_http_v2_out_frame_t *free_frames;
ngx_chain_t *free_frame_headers;
ngx_chain_t *free_bufs;
diff --git a/src/http/v2/ngx_http_v2_filter_module.c b/src/http/v2/ngx_http_v2_filter_module.c
--- a/src/http/v2/ngx_http_v2_filter_module.c
+++ b/src/http/v2/ngx_http_v2_filter_module.c
@@ -1669,22 +1669,34 @@ static ngx_http_v2_out_frame_t *
ngx_http_v2_filter_get_data_frame(ngx_http_v2_stream_t *stream,
size_t len, ngx_chain_t *first, ngx_chain_t *last)
{
- u_char flags;
- ngx_buf_t *buf;
- ngx_chain_t *cl;
- ngx_http_v2_out_frame_t *frame;
+ u_char flags;
+ ngx_buf_t *buf;
+ ngx_chain_t *cl;
+ ngx_http_v2_out_frame_t *frame;
+ ngx_http_v2_connection_t *h2c;

frame = stream->free_frames;
+ h2c = stream->connection;

if (frame) {
stream->free_frames = frame->next;

- } else {
+ } else if (h2c->frames < 10000) {
frame = ngx_palloc(stream->request->pool,
sizeof(ngx_http_v2_out_frame_t));
if (frame == NULL) {
return NULL;
}
+
+ stream->frames++;
+ h2c->frames++;
+
+ } else {
+ ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
+ "http2 flood detected");
+
+ h2c->connection->error = 1;
+ return NULL;
}

flags = last->buf->last_buf ? NGX_HTTP_V2_END_STREAM_FLAG : 0;
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[nginx] HTTP/2: limited number of DATA frames.

Maxim Dounin 74 August 13, 2019 01:02PM



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