[nginx] Added size check to ngx_http_alloc_large_header_buffer().

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/8253424d1aff
branches:  
changeset: 7690:8253424d1aff
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu Aug 06 05:02:22 2020 +0300
description:
Added size check to ngx_http_alloc_large_header_buffer().

This ensures that copying won't write more than the buffer size
even if the buffer comes from hc->free and it is smaller than the large
client header buffer size in the virtual host configuration.  This might
happen if size of large client header buffers is different in name-based
virtual hosts, similarly to the problem with number of buffers fixed
in 6926:e662cbf1b932.

diffstat:

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

diffs (16 lines):

diff -r da8d758aabeb -r 8253424d1aff src/http/ngx_http_request.c
--- a/src/http/ngx_http_request.c	Mon Jul 27 16:02:15 2020 +0300
+++ b/src/http/ngx_http_request.c	Thu Aug 06 05:02:22 2020 +0300
@@ -1647,6 +1647,12 @@ ngx_http_alloc_large_header_buffer(ngx_h
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                    "http large header copy: %uz", r->header_in->pos - old);
 
+    if (r->header_in->pos - old > b->end - b->start) {
+        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                      "too large header to copy");
+        return NGX_ERROR;
+    }
+
     new = b->start;
 
     ngx_memcpy(new, old, r->header_in->pos - old);