[tor-bugs] #31408 [Core Tor/Tor]: torrc : ClientOnionAuthDir after include directives breaks client to v2 services

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#31408: torrc : ClientOnionAuthDir after include directives breaks client to v2
services
----------------------------------------+----------------------------------
 Reporter:  xaho                        |          Owner:  asn
     Type:  defect                      |         Status:  needs_review
 Priority:  Very High                   |      Milestone:  Tor:
                                        |  0.4.2.x-final
Component:  Core Tor/Tor                |        Version:  Tor: 0.4.0.5
 Severity:  Normal                      |     Resolution:
 Keywords:  tor-hs regression 042-must  |  Actual Points:
Parent ID:                              |         Points:
 Reviewer:                              |        Sponsor:
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Changes (by Jigsaw52):

 * status:  assigned => needs_review


Comment:

 The cause of this problem is a bug in the processing of included folders
 containing files with only comments or whitespace. I was able to reproduce
 this problem with the following configuration:

 torrc:
 {{{
 %include /etc/tor/torrc.d/
 Log notice stderr # can be any valid option
 }}}

 /etc/tor/torrc.d/01_invalid:
 {{{
 InvalidOption
 }}}

 /etc/tor/torrc.d/02_comment:
 {{{
 # comment
 }}}

 Running tor --verify-config -f torrc will incorrectly identify this as a
 valid configuration despite the invalid option on
 /etc/tor/torrc.d/01_invalid.

 The bug is that any files on a %included folder where the last file
 contains only comments or whitespace are being ignored. Also the bug is
 only triggered if there is a valid option after the %include.

 The cause of this bug is that, when creating the list of configurations
 options from the included files, a pointer to the last element of the list
 is incorrectly set to NULL when processing a file with only comments or
 whitespace. This can cause the options list to be built incorrectly,
 causing this behaviour.

 I've made a pull request with a fix for this problem and a test case:
 https://github.com/torproject/tor/pull/1347

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31408#comment:11>
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