changeset 7041:6169dbad37d8

Upstream: fixed running posted requests (ticket #788). Previously, the upstream resolve handler always called ngx_http_run_posted_requests() to run posted requests after processing the resolver response. However, if the handler was called directly from the ngx_resolve_name() function (for example, if the resolver response was cached), running posted requests from the handler could lead to the following errors: - If the request was scheduled for termination, it could actually be terminated in the resolve handler. Upper stack frames could reference the freed request object in this case. - If a significant number of requests were posted, and for each of them the resolve handler was called directly from the ngx_resolve_name() function, posted requests could be run recursively and lead to stack overflow. Now ngx_http_run_posted_requests() is only called from asynchronously invoked resolve handlers.
author Roman Arutyunyan <arut@nginx.com>
date Wed, 14 Jun 2017 20:13:41 +0300
parents d49b74a683b1
children bd2f97a3aecc
files src/http/ngx_http_upstream.c
diffstat 1 files changed, 6 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -1143,11 +1143,14 @@ ngx_http_upstream_cache_check_range(ngx_
 static void
 ngx_http_upstream_resolve_handler(ngx_resolver_ctx_t *ctx)
 {
+    ngx_uint_t                     run_posted;
     ngx_connection_t              *c;
     ngx_http_request_t            *r;
     ngx_http_upstream_t           *u;
     ngx_http_upstream_resolved_t  *ur;
 
+    run_posted = ctx->async;
+
     r = ctx->data;
     c = r->connection;
 
@@ -1211,7 +1214,9 @@ ngx_http_upstream_resolve_handler(ngx_re
 
 failed:
 
-    ngx_http_run_posted_requests(c);
+    if (run_posted) {
+        ngx_http_run_posted_requests(c);
+    }
 }