[privoxy-users] [ ijbswa-Support Requests-3615324 ] Bug? Privoxy crashes when visiting one particul

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 454-5900

Support Requests item #3615324, was opened at 2014-01-30 07:13
Message generated for change (Comment added) made by diem
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=211118&aid=3615324&group_id=11118

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: other
Group: 3.0.21
Status: Open
Priority: 5
Private: No
Submitted By: Korda (faxotherapy)
Assigned to: Fabian Keil (fabiankeil)
Summary: Bug? Privoxy crashes when visiting one particular site

Initial Comment:
dear support, when Privoxy is used in “Advanced” mode, Privoxy crashes on that particular site: http://lexpress.fr

Once on this website, click any link such as “Politique” from the top bar. Results: Privoxy no longer works.

I managed to replicate this on another computer.

Thank your for your help.

----------------------------------------------------------------------

>Comment By: Ian Silvester (diem)
Date: 2014-01-31 10:19

Message:
Thanks Fabian,

I'll look into things in that regard and, if you're right, see if I can
reduce PCRE's recursion limit appropriately for the next release.

Cheers,

Ian

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 10:11

Message:
Raphael, you can keep the exception for now, but as Ian mentioned this is
only a work-around.

Now that we know the offending filter we can probably rewrite it to require
less stack space. I'll look into this in a couple of days.

Having said that, the filter also doesn't seem particular useful to me, so
we should probably remove it from the advanced settings anyway.

Ian, I assume that the crash isn't a pcre regression, but the expected (but
inconvenient) behavior if pcre's compiled-in recursion limit is too high
for the operating systems stack size limit. In case you're interested, the
relevant documentation is in the pcre man pages pcrestack and pcrebuild.

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 08:41

Message:
dear Ian, I'm very grateful to you and Fabian for all your explanation and
your swift reply. Extremely informative indeed and helpful. Hopefully, our
recent interactions should make Privoxy even better.

PCRE, of course! I ought to have thought about it… ;-)

Exciting weekend to all of you.

Raphael (the real name)

----------------------------------------------------------------------

Comment By: Ian Silvester (diem)
Date: 2014-01-31 07:09

Message:
Hi Korda,

I'm the OS X maintainer for Privoxy and thought I ought to chime in.

Just in passing, the behaviour you see with startPrivoxy.sh stating that
Privoxy is 'already loaded' is expected (if counter-intuitive) behaviour.
On OS X we leverage launchd which does not notice that Privoxy has
terminated unexpectedly (potentially due to the way I've written the
launchItem). So far as launchd is concerned therefore the daemon remains
'loaded' because that's what it's own records say. Running stopPrivoxy.sh
updates launchd's internal accounting so that you can once again start it.
None of which has anything to do with why it crashes of course!

Since the failure is in the PCRE library, I will review the changelog in
that project. The version currently bundled with Privoxy on OS X is 8.21
whilst the most recent release is 8.34, so there is scope for a fault in
that project being the cause of the issue that Fabian has worked around for
you.

In terms of how to identify the cause, its a case of reviewing the Privoxy
log to see what is the last item processed before the crash (or other
unexpected behaviour since crashes are extremely rare) and reconfiguring
Privoxy such that it would not filter the item in question. Not to take
anything away from Fabian's skill in these matters though - he does have a
real skill in focussing on that that matters and ignoring irrelevancies!

Kind regards,

Ian

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 06:06

Message:
Added to “user.action” file the following:
{-filter{content-cookies}}
.lexpansion.com/fonts/

Results: NO CRASH

CONGRATULATION TO YOU ; you are a real sherlock!

So, what's next? Should I keep it as is with the add-on you suggested? BTW,
how can I isolate the problem next time? So, I don't bother you every time
when this happens again.

Thank you.

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 05:48

Message:
The log file suggests that Privoxy is running out of stack space while
filtering
http://static.lexpansion.com/fonts/metaserifpro_medium/metaserifpro_medium.svg
(served with an incorrectContent-Type) with the content-cookies filter.

To confirm this theory, please try to reproduce the problem with the filter
disabled:

{-filter{content-cookies}}
.lexpansion.com/fonts/

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 05:30

Message:
I ran it without custom filters

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 05:28

Message:
Your request attached. Thanks for the clue.

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 05:16

Message:
That's indeed very helpful.

I'm not too familiar with Mac OS X crash reports, but it looks like Privoxy
is running out of stack space due to a deep recursion in pcre.

If that's the case, increasing the stack size limit should prevent the
crashes but this should only be the last resort.

Please reproduce the problem once more, with "debug 64" added to the config
and provide another Privoxy log excerpt and crash report.

It would also be useful to know if you can reproduce the problem without
any custom filters.

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 04:18

Message:
Good news! I've got the log you wanted… Hopefully!

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 04:14

Message:
My system: OS 10.8.5 ; Privoxy 3.0.21 ; binary downloaded from your server,
with the easy install for Mac OS X. The issue also appears on OS 10.6.8,
BTW. I'm going to deliver new logs from system soon. 

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 04:04

Message:
Hello Fabian,

let me think. In the meantime, have a look at my Proxy config. Didn't put
my easy list scripts to save disk space. Thank you. If necessary, can I
humbly suggest you use an app to compare my config versus yours, such as
TextWrangler, etc.

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 03:52

Message:
Thanks for the log excerpt, unfortunately it doesn't seem to show any
obvious problem except that it ends prematurely.

Could you provide some more details about the operating system Privoxy runs
on an whether or not you are using an official binary?

Is there a way to get an OS-specific "crash report", for example a back
trace?

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 03:27

Message:
You should see “MY_LOG.log.zip”

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 03:27

Message:
I have activated the debug directives you mentioned. Please, see new log
attached. The last log line printed by Privoxy is “00000280 Connect: to
static.lexpansion.com successful” which led Privoxy to shut down.

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 03:10

Message:
Please use the debug directives:

debug     1 # Log the destination for each request Privoxy let through. See
also debug 1024.
debug     2 # show each connection status
debug     4 # show I/O status
debug     8 # show header parsing
debug   128 # debug redirects
debug   256 # debug GIF de-animation
debug   512 # Common Log Format
debug  1024 # Log the destination for requests Privoxy didn't let through,
and the reason why.
debug  4096 # Startup banner and warnings.
debug  8192 # Non-fatal errors

as described at
http://www.privoxy.org/user-manual/contact.html#SUFFICIENT-INFORMATION

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-31 03:01

Message:
Hello Fabian, here's the log. I have removed the first few hundred lines…
I hope it will be OK. Thanks again for your patience. 

I have “downgraded” to “medium“ aggressiveness. I hope I'll be able
to revert back to “advanced” at some point. I experienced, again, this
morning, a shutdown of Privoxy visiting “www.lexpansion.lexpress.fr”
domain. 

When it happens, Privoxy daemon seems apparently killed. However, when I go
to reactivate Privoxy using “startPrivoxy.sh", it tells me that Privoxy
is already loaded. I have to exec first “stopPrivoxy.sh”, then
“startPrivoxy.sh” afterwards. Then, Privoxy is up and running again.

Thank you for your support.

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-31 02:47

Message:
According to SF, there are "No Files Currently Attached".

In case of a real crash, it's probably sufficient to post the last few
hundred lines in which case you probably don't even need to compress the
excerpt to stay below the limit.

If not, please use a common compression format like zip or gz.

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-30 08:30

Message:
attached file 2/2 (use 7zX app. Easy to find)

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-30 08:29

Message:
attached file 1/2 (use 7zX app. Easy to find)

Thanks

----------------------------------------------------------------------

Comment By: Korda (faxotherapy)
Date: 2014-01-30 08:23

Message:
Hello, I would like to send the log file, but it's 310 K > 256 KB

Frustrating. Don't want to remove any potential lines that could help. Is
there any alternative to send you? Thank you

----------------------------------------------------------------------

Comment By: Fabian Keil (fabiankeil)
Date: 2014-01-30 07:21

Message:
Thanks for the report, I can't reproduce this (so far), though.

Please provide a log excerpt as described at:
http://www.privoxy.org/user-manual/contact.html#SUFFICIENT-INFORMATION

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=211118&aid=3615324&group_id=11118

[privoxy-users] [ ijbswa-Support Requests-3615324 ] Bug? Privoxy crashes when visiting one particul

HTTP proxy to block ads and customize webpages

[privoxy-users] [ ijbswa-Support Requests-3615324 ] Bug? Privoxy crashes when visiting one particular site