Re: help needed to complete regression fix for apache2 Bug#858373
Hi Antoine,
On Wednesday, 19 July 2017 15:45:20 CEST Antoine Beaupre wrote:
> As I mentioned in the #858373 bug report, I started looking at fixing
> the regression introduced by the 2.2.22-13+deb7u8 upload, part of
> DLA-841-1. The problem occurs when a CGI(d) ErrorDocument is configured
> to handle 400 error messages that can be triggered with a simple "GET /
> HTTP/1.0\n\n". Such a request segfaults Apache in Wheezy right now.
> Unfortunately, re-introducing the protocol initialization code isn't
> sufficient: it does fix the segfaults, but the ErrorDocument handling is
> not quite working yet. Instead of seeing the output of the
> ErrorDocument, after 10 seconds, I get the raw 400 message, doubled with
> a 500 error document warning:
> Note that I have also tried to see if sending "\r\n" instead of just
> "\n" in my "hello world" example would work around the issue: it
> doesn't, unfortunately.
>
> I am at a loss as where to go from here, to be honest. The patch
> (attached) at least fixes the segfault, which resolves the primary issue
> at hand here (DoS by crashing processes!) but it would be nice to
> actually fix the ErrorDocument as well..
This sounds familiar. Maybe it's simply broken in 2.2.22. Can you compare with
2.2.22-13+deb7u7 if that bug has been there already?
In 2.2.30, there is this fix, which is obviously missing from 2.2.22:
*) core, modules: Avoid error response/document handling by the core if some
handler or input filter already did it while reading the request (causing
a double response body). [Yann Ylavic]
I could not find a changelog entry about the 10s delay, but it's possible that
that has been fixed as well. If the issue is not a regression, you should
simply release the patch that you have. The fix for the error document seems
rather invasive:
https://svn.apache.org/r1683808
Cheers,
Stefan
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