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[nginx] OCSP: fixed use-after-free on error.

Roman Arutyunyan
June 19, 2020 10:04AM
details: https://hg.nginx.org/nginx/rev/1ece2ac2555a
branches:
changeset: 7667:1ece2ac2555a
user: Roman Arutyunyan <arut@nginx.com>
date: Mon Jun 15 20:17:16 2020 +0300
description:
OCSP: fixed use-after-free on error.

When validating second and further certificates, ssl callback could be called
twice to report the error. After the first call client connection is
terminated and its memory is released. Prior to the second call and in it
released connection memory is accessed.

Errors triggering this behavior:
- failure to create the request
- failure to start resolving OCSP responder name
- failure to start connecting to the OCSP responder

The fix is to rearrange the code to eliminate the second call.

diffstat:

src/event/ngx_event_openssl_stapling.c | 43 ++++++++++++++++-----------------
1 files changed, 21 insertions(+), 22 deletions(-)

diffs (108 lines):

diff -r 8cf31489b479 -r 1ece2ac2555a src/event/ngx_event_openssl_stapling.c
--- a/src/event/ngx_event_openssl_stapling.c Mon Jun 15 17:35:26 2020 -0400
+++ b/src/event/ngx_event_openssl_stapling.c Mon Jun 15 20:17:16 2020 +0300
@@ -980,6 +980,7 @@ ngx_ssl_ocsp_validate_next(ngx_connectio
if (ocsp->ncert == n - 1 || (ocf->depth == 2 && ocsp->ncert == 1)) {
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
"ssl ocsp validated, certs:%ui", ocsp->ncert);
+ rc = NGX_OK;
goto done;
}

@@ -988,7 +989,8 @@ ngx_ssl_ocsp_validate_next(ngx_connectio

ctx = ngx_ssl_ocsp_start(c->log);
if (ctx == NULL) {
- goto failed;
+ rc = NGX_ERROR;
+ goto done;
}

ocsp->ctx = ctx;
@@ -1012,8 +1014,9 @@ ngx_ssl_ocsp_validate_next(ngx_connectio
ctx->uri = ocf->uri;
ctx->port = ocf->port;

- if (ngx_ssl_ocsp_responder(c, ctx) != NGX_OK) {
- goto failed;
+ rc = ngx_ssl_ocsp_responder(c, ctx);
+ if (rc != NGX_OK) {
+ goto done;
}

if (ctx->uri.len == 0) {
@@ -1025,7 +1028,7 @@ ngx_ssl_ocsp_validate_next(ngx_connectio
rc = ngx_ssl_ocsp_cache_lookup(ctx);

if (rc == NGX_ERROR) {
- goto failed;
+ goto done;
}

if (rc == NGX_DECLINED) {
@@ -1051,12 +1054,12 @@ ngx_ssl_ocsp_validate_next(ngx_connectio

done:

- ocsp->status = NGX_OK;
- return;
-
-failed:
-
- ocsp->status = NGX_ERROR;
+ ocsp->status = rc;
+
+ if (c->ssl->in_ocsp) {
+ c->ssl->handshaked = 1;
+ c->ssl->handler(c);
+ }
}


@@ -1073,22 +1076,16 @@ ngx_ssl_ocsp_handler(ngx_ssl_ocsp_ctx_t

rc = ngx_ssl_ocsp_verify(ctx);
if (rc != NGX_OK) {
- ocsp->status = rc;
- ngx_ssl_ocsp_done(ctx);
goto done;
}

rc = ngx_ssl_ocsp_cache_store(ctx);
if (rc != NGX_OK) {
- ocsp->status = rc;
- ngx_ssl_ocsp_done(ctx);
goto done;
}

if (ctx->status != V_OCSP_CERTSTATUS_GOOD) {
ocsp->cert_status = ctx->status;
- ocsp->status = NGX_OK;
- ngx_ssl_ocsp_done(ctx);
goto done;
}

@@ -1096,15 +1093,17 @@ ngx_ssl_ocsp_handler(ngx_ssl_ocsp_ctx_t

ngx_ssl_ocsp_validate_next(c);

+ return;
+
done:

- if (ocsp->status == NGX_AGAIN || !c->ssl->in_ocsp) {
- return;
+ ocsp->status = rc;
+ ngx_ssl_ocsp_done(ctx);
+
+ if (c->ssl->in_ocsp) {
+ c->ssl->handshaked = 1;
+ c->ssl->handler(c);
}
-
- c->ssl->handshaked = 1;
-
- c->ssl->handler(c);
}


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[nginx] OCSP: fixed use-after-free on error.

Roman Arutyunyan 68 June 19, 2020 10:04AM



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