[nginx] Request body: added alert to catch duplicate body saving.

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/96e09beaa2cf
branches:  
changeset: 7912:96e09beaa2cf
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Sun Aug 29 22:20:54 2021 +0300
description:
Request body: added alert to catch duplicate body saving.

If due to an error ngx_http_request_body_save_filter() is called
more than once with rb->rest == 0, this used to result in a segmentation
fault.  Added an alert to catch such errors, just in case.

diffstat:

 src/http/ngx_http_request_body.c |  6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diffs (16 lines):

diff -r d869e43643ac -r 96e09beaa2cf src/http/ngx_http_request_body.c
--- a/src/http/ngx_http_request_body.c	Sun Aug 29 22:20:49 2021 +0300
+++ b/src/http/ngx_http_request_body.c	Sun Aug 29 22:20:54 2021 +0300
@@ -1246,6 +1246,12 @@ ngx_http_request_body_save_filter(ngx_ht
 
     if (rb->temp_file || r->request_body_in_file_only) {
 
+        if (rb->bufs && rb->bufs->buf->in_file) {
+            ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                          "body already in file");
+            return NGX_HTTP_INTERNAL_SERVER_ERROR;
+        }
+
         if (ngx_http_write_request_body(r) != NGX_OK) {
             return NGX_HTTP_INTERNAL_SERVER_ERROR;
         }