pcre_exec() failed: -10

[Maxim Dounin]

Hello!

On Tue, Jan 26, 2016 at 10:03:16PM +0530, Krishna PMV wrote:

> Hello,
> 
> I've a rule below in nginx config to 404 if the argument of search query is
> a non printable ascii character. Nginx is compiled with pcre and pcre
> seem** (refer 4.d below) to have utf8 support and unicode support enabled
> but nginx fails with "pcre_exec() failed: -10" error when it encounters the
> regex.
> 
> Any pointers, please? Please refer below for more details.
> 
> TIA,
> 
> Krishna!
> 
> *1. from nginx config*
> 
> if ($args ~ "(*UTF8)^.*[^\x21-\x7E].*$") {
> 
>          return 404;
> 
>      }
> 
> *..*
> 
> 
> *2. from access log:*
> 
> 54.169.206.188 [26/Jan/2016:20:29:10
> /search?userQuery=Taurm\xE9+Taurme+Corporate+Casual+Slip+On+Shoe+()
> 
> *3. from error log:*
> 
> 2016/01/26 20:29:10 [alert] 27700#0: *43933484 on
> "userQuery=Taurm+Taurme+Corporate+Casual+Slip+On+Shoe+()" using
> "(*UTF8)^.*[^\x00-\x7F].*$", client: 54.169.206.188, server:
> search.paytm.com, request: "GET
> /search?userQuery=Taurm+Taurme+Corporate+Casual+Slip+On+Shoe+() HTTP/1.1",
> host: "search.paytm.com"

The error is returned by PCRE due to an invalid UTF-8 string being 
checked as UTF-8 one.  Note "\xE9" in the access log entry.  Some 
additional information can be found in the pcreunicode manpage.

-- 
Maxim Dounin
http://nginx.org/