Exploit for Nginx Remote Integer Overflow Vulnerability

## https://sploitus.com/exploit?id=SSV:96273
A security issue was identified in nginx range filter.  A specially
crafted request might result in an integer overflow and incorrect
processing of ranges, potentially resulting in sensitive information
leak (CVE-2017-7529).

When using nginx with standard modules this allows an attacker to
obtain a cache file header if a response was returned from cache.
In some configurations a cache file header may contain IP address
of the backend server or other sensitive information.

Besides, with 3rd party modules it is potentially possible that
the issue may lead to a denial of service or a disclosure of
a worker process memory.  No such modules are currently known though.

The issue affects nginx 0.5.6 - 1.13.2.
The issue is fixed in nginx 1.13.3, 1.12.1.

For older versions, the following configuration can be used
as a temporary workaround:
```
max_ranges 1;
```

**patch**
```
diffsrc/http/modules/ngx_http_range_filter_module.c b/src/http/modules/ngx_http_range_filter_module.c
--- src/http/modules/ngx_http_range_filter_module.c
+++ src/http/modules/ngx_http_range_filter_module.c
@@ -377,6 +377,10 @@ ngx_http_range_parse(ngx_http_request_t 
             range->start = start;
             range->end = end;
 
+            if (size > NGX_MAX_OFF_T_VALUE - (end - start)) {
+                return NGX_HTTP_RANGE_NOT_SATISFIABLE;
+            }
+
             size += end - start;
 
             if (ranges-- == 0) {
```