From 92111c92e5860ff6338dc8ded8e3805189d02fc7 Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Tue, 11 Jul 2017 16:06:23 +0300 Subject: 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. --- src/http/modules/ngx_http_range_filter_module.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'src/http/modules') diff --git a/src/http/modules/ngx_http_range_filter_module.c b/src/http/modules/ngx_http_range_filter_module.c index 7ad9db9dd..ac910fdfe 100644 --- 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 *r, ngx_http_range_filter_ctx_t *ctx, 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) { -- cgit