# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1360466835 0
# Node ID 48d1606107d44e721f7a7f1246def67b97e64023
# Parent  30fe1b1acf933093a8403fb1e32daf1cb3460409
Merge of r4965: upstream: fixed SIGSEGV with the "if" directive.

Configuration like

    location / {
        set $true 1;

        if ($true) {
            proxy_pass http://backend;
        }

        if ($true) {
            # nothing
        }
    }

resulted in segmentation fault due to NULL pointer dereference as the
upstream configuration wasn't initialized in an implicit location created
by the last if(), but the r->content_handler was set due to first if().

Instead of committing a suicide by dereferencing a NULL pointer, return
500 (Internal Server Error) in such cases, i.e. if uscf is NULL.  Better
fix would be to avoid such cases by fixing the "if" directive handling,
but it's out of scope of this patch.

Prodded by Piotr Sikora.

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -636,6 +636,14 @@ ngx_http_upstream_init_request(ngx_http_
 
 found:
 
+    if (uscf == NULL) {
+        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                      "no upstream configuration");
+        ngx_http_upstream_finalize_request(r, u,
+                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
+        return;
+    }
+
     if (uscf->peer.init(r, uscf) != NGX_OK) {
         ngx_http_upstream_finalize_request(r, u,
                                            NGX_HTTP_INTERNAL_SERVER_ERROR);