# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1499778383 -10800
# Node ID 1adc6b0d5eaa3bddd6bb1ef7b78b9511d536f14e
# Parent  f38e906c81668077497fdb1fa377c48c43477bc5
Range filter: protect from total size overflows.

The overflow can be used to circumvent the restriction on total size of
ranges introduced in c2a91088b0c0 (1.1.2).  Additionally, overflow
allows producing ranges with negative start (such ranges can be created
by using a suffix, "bytes=-100"; normally this results in 200 due to
the total size check).  These can result in the following errors in logs:

[crit] ... pread() ... failed (22: Invalid argument)
[alert] ... sendfile() failed (22: Invalid argument)

When using cache, it can be also used to reveal cache file header.
It is believed that there are no other negative effects, at least with
standard nginx modules.

In theory, this can also result in memory disclosure and/or segmentation
faults if multiple ranges are allowed, and the response is returned in a
single in-memory buffer.  This never happens with standard nginx modules
though, as well as known 3rd party modules.

Fix is to properly protect from possible overflow when incrementing size.

diff --git a/src/http/modules/ngx_http_range_filter_module.c b/src/http/modules/ngx_http_range_filter_module.c
--- a/src/http/modules/ngx_http_range_filter_module.c
+++ b/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) {