Upstream: ngx_post_event() instead of upgraded call (ticket #503).

If a request is finalized in the first call to the
ngx_http_upstream_process_upgraded() function, e.g., because upstream
server closed the connection for some reason, in the second call
the u->peer.connection pointer will be null, resulting in segmentation
fault.

Fix is to avoid second direct call, and post event instead.  This ensures
that ngx_http_upstream_process_upgraded() won't be called again if
a request is finalized.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index ffdffcf07..d99d85454 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2456,7 +2456,9 @@ ngx_http_upstream_upgrade(ngx_http_request_t *r, ngx_http_upstream_t *u)
     if (u->peer.connection->read->ready
         || u->buffer.pos != u->buffer.last)
     {
+        ngx_post_event(c->read, &ngx_posted_events);
         ngx_http_upstream_process_upgraded(r, 1, 1);
+        return;
     }
 
     ngx_http_upstream_process_upgraded(r, 0, 1);