File nghttp2-CVE-2023-35945.patch of Package nghttp2.30852
From ce385d3f55a4b76da976b3bdf71fe2deddf315ba Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Fri, 14 Jul 2023 20:52:03 +0900
Subject: [PATCH] Fix memory leak
This commit fixes memory leak that happens when PUSH_PROMISE or
HEADERS frame cannot be sent, and nghttp2_on_stream_close_callback
fails with a fatal error. For example, if GOAWAY frame has been
received, a HEADERS frame that opens new stream cannot be sent.
This issue has already been made public via CVE-2023-35945 [1] issued
by envoyproxy/envoy project. During embargo period, the patch to fix
this bug was accidentally submitted to nghttp2/nghttp2 repository [2].
And they decided to disclose CVE early. I was notified just 1.5 hours
before disclosure. I had no time to respond.
PoC described in [1] is quite simple, but I think it is not enough to
trigger this bug. While it is true that receiving GOAWAY prevents a
client from opening new stream, and nghttp2 enters error handling
branch, in order to cause the memory leak,
nghttp2_session_close_stream function must return a fatal error.
nghttp2 defines 2 fatal error codes:
- NGHTTP2_ERR_NOMEM
- NGHTTP2_ERR_CALLBACK_FAILURE
NGHTTP2_ERR_NOMEM, as its name suggests, indicates out of memory. It
is unlikely that a process gets short of memory with this simple PoC
scenario unless application does something memory heavy processing.
NGHTTP2_ERR_CALLBACK_FAILURE is returned from application defined
callback function (nghttp2_on_stream_close_callback, in this case),
which indicates something fatal happened inside a callback, and a
connection must be closed immediately without any further action. As
nghttp2_on_stream_close_error_callback documentation says, any error
code other than 0 or NGHTTP2_ERR_CALLBACK_FAILURE is treated as fatal
error code. More specifically, it is treated as if
NGHTTP2_ERR_CALLBACK_FAILURE is returned. I guess that envoy returns
NGHTTP2_ERR_CALLBACK_FAILURE or other error code which is translated
into NGHTTP2_ERR_CALLBACK_FAILURE.
[1] https://github.com/envoyproxy/envoy/security/advisories/GHSA-jfxv-29pc-x22r
[2] https://github.com/nghttp2/nghttp2/pull/1929
---
lib/nghttp2_session.c | 10 +++++-----
tests/nghttp2_session_test.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 5 deletions(-)
diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c
index 7509ceb5..71858a39 100644
--- a/lib/nghttp2_session.c
+++ b/lib/nghttp2_session.c
@@ -3296,6 +3296,7 @@ static ssize_t nghttp2_session_mem_send_internal(nghttp2_session *session,
if (rv < 0) {
int32_t opened_stream_id = 0;
uint32_t error_code = NGHTTP2_INTERNAL_ERROR;
+ int rv2 = 0;
DEBUGF("send: frame preparation failed with %s\n",
nghttp2_strerror(rv));
@@ -3338,19 +3339,18 @@ static ssize_t nghttp2_session_mem_send_internal(nghttp2_session *session,
}
if (opened_stream_id) {
/* careful not to override rv */
- int rv2;
rv2 = nghttp2_session_close_stream(session, opened_stream_id,
error_code);
-
- if (nghttp2_is_fatal(rv2)) {
- return rv2;
- }
}
nghttp2_outbound_item_free(item, mem);
nghttp2_mem_free(mem, item);
active_outbound_item_reset(aob, mem);
+ if (nghttp2_is_fatal(rv2)) {
+ return rv2;
+ }
+
if (rv == NGHTTP2_ERR_HEADER_COMP) {
/* If header compression error occurred, should terminiate
connection. */
diff --git a/tests/nghttp2_session_test.c b/tests/nghttp2_session_test.c
index b55ff534..74352426 100644
--- a/tests/nghttp2_session_test.c
+++ b/tests/nghttp2_session_test.c
@@ -584,6 +584,15 @@ static int on_stream_close_callback(nghttp2_session *session, int32_t stream_id,
return 0;
}
+static int fatal_error_on_stream_close_callback(nghttp2_session *session,
+ int32_t stream_id,
+ uint32_t error_code,
+ void *user_data) {
+ on_stream_close_callback(session, stream_id, error_code, user_data);
+
+ return NGHTTP2_ERR_CALLBACK_FAILURE;
+}
+
static ssize_t pack_extension_callback(nghttp2_session *session, uint8_t *buf,
size_t len, const nghttp2_frame *frame,
void *user_data) {
@@ -4296,6 +4305,8 @@ void test_nghttp2_session_on_goaway_received(void) {
nghttp2_frame frame;
int i;
nghttp2_mem *mem;
+ const uint8_t *data;
+ ssize_t datalen;
mem = nghttp2_mem_default();
user_data.frame_recv_cb_called = 0;
@@ -4337,6 +4348,29 @@ void test_nghttp2_session_on_goaway_received(void) {
nghttp2_frame_goaway_free(&frame.goaway, mem);
nghttp2_session_del(session);
+
+ /* Make sure that no memory leak when stream_close callback fails
+ with a fatal error */
+ memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
+ callbacks.on_stream_close_callback = fatal_error_on_stream_close_callback;
+
+ memset(&user_data, 0, sizeof(user_data));
+
+ nghttp2_session_client_new(&session, &callbacks, &user_data);
+
+ nghttp2_frame_goaway_init(&frame.goaway, 0, NGHTTP2_NO_ERROR, NULL, 0);
+
+ CU_ASSERT(0 == nghttp2_session_on_goaway_received(session, &frame));
+
+ nghttp2_submit_request(session, NULL, reqnv, ARRLEN(reqnv), NULL, NULL);
+
+ datalen = nghttp2_session_mem_send(session, &data);
+
+ CU_ASSERT(NGHTTP2_ERR_CALLBACK_FAILURE == datalen);
+ CU_ASSERT(1 == user_data.stream_close_cb_called);
+
+ nghttp2_frame_goaway_free(&frame.goaway, mem);
+ nghttp2_session_del(session);
}
void test_nghttp2_session_on_window_update_received(void) {
--
2.35.3
