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Re: svn segfault when using svn+ssh schema




On 16/01/2017 20:26, Jon Turney wrote:
> On 16/01/2017 20:07, Sam Edge wrote:
>> On 09/01/2017 19:07, Sam Edge wrote:
>>> On 09/01/2017 02:04, Eliot Moss wrote:
>>>> On 1/8/2017 3:45 PM, David Rothenberger wrote:
>>>>> On 1/8/2017 6:12 AM, Sam Edge wrote:
>>>>>> I've seen a number of 'svn segfault' threads on the mailing list
>>>>>> archive
>>>>>> but none of them seem to cover this specific failure mode.
>>>>>> (Apologies if
>>>>>> one of them does!)
>>>>>>
>>>>>> I'm getting segfaults from svn but only when using ssh as the
>>>>>> schema.
>>>>>> The following three commands are all accessing the same server, the
>>>>>> name
>>>>>> of which has been changed to protect the guilty.
>>>>>>
>>>>>> --------
>>>>>> SamEdge@thor ~
>>>>>> $ ssh cmserver.XXXXXX.com
>>>>>> ( success ( 2 2 ( ) ( edit-pipeline svndiff1 absent-entries
>>>>>> commit-revprops depth log-revprops atomic-revprops partial-replay
>>>>>> inherited-props ephemeral-txnprops file-revs-reverse ) ) )
>>>>>> SamEdge@thor ~
>>>>>> $ svn ls svn+ssh://cmserver.XXXXXX.com/edl/
>>>>>> Segmentation fault (core dumped)
>>>> Assuming this is repeatable behavior, perhaps getting a trace using
>>>> strace would reveal some more useful information.
>>>>
>>>> Regards - Eliot Moss
>>>>
>>> Good idea.
>>>
>>> Strangely, on another Windows 7 64-bit machine svn+ssh to the same
>>> server is working fine for me. The most significant differences are
>>> that
>>> the 'working' machine is running Windows 7 Pro on an Intel CPU with
>>> Sophos AV and domain accounts whereas the 'failing' machine is
>>> Windows 7
>>> Home Premium on an AMD with MS Security Essentials and local accounts.
>>> These differences may or may not be relevant of course.
>>>
>>> Anyway, attached are the two strace outputs. Diffing them suggests that
>>> it's segfaulting in the fork() "system" call.
>
> Not quite, this strace has...
>
>> --- Process 5436 loaded C:\cygwin64\lib\sasl2_3\cygcrammd5-3.dll at
>> 00000003EA090000
>> --- Process 5436, exception c0000005 at 00000003EA023780
>> --- Process 5436 unloaded DLL at 00000003EA090000
>>   333   52465 [main] svn 5436 seterrno_from_win_error:
>> /home/corinna/src/cygwin/cygwin-2.6.1/cygwin-2.6.1-1.x86_64/src/newlib-cygwin/winsup/cygwin/dlfcn.cc:304
>> windows error 998
>>    24   52489 [main] svn 5436 geterrno_from_win_error: windows error
>> 998 == errno 14
>>    20   52509 [main] svn 5436 dlopen: ret 0x0
>
> and then a bit later
>
>>    21   91851 [main] svn 5436 fork: entering
>>   168   92019 [main] svn 5436 sig_send: sendsig 0x80, pid 5436,
>> signal -72, its_me 1
>>    19   92038 [main] svn 5436 sig_send: wakeup 0x28C
>>    24   92062 [main] svn 5436 sig_send: Waiting for pack.wakeup 0x28C
>>    36   92098 [sig] svn 5436 wait_sig: signalling pack.wakeup 0x28C
>>    27   92125 [main] svn 5436 sig_send: returning 0x0 from sending
>> signal -72
>> --- Process 5436, exception c0000005 at 0000000180053D3F
>
> So it looks like perhaps cygcrammd5 is faulting during it's DllMain,
> and perhaps this leaves things in a state that dll_list::topsort can't
> handle...
>
>>> I don't have time in the week to run it in a debug session but I'll try
>>> to do so at the weekend given the advice I've been given here. I will
>>> also do a rebaseall after I've tracked down the
>>>
>>> Thanks for the feedback folks. Much appreciated.
>>>
>>> BR
>>
>> Hi again.
>>
>> I've downloaded the debug symbols for subversion & the Cygwin dll and
>> run the command in gdb. Output attached. Not really giving me any clues
>> so far.
>
> You also need the symbols for the DLL loaded at the faulting address.
>
> From previous information I'd guess that is cyrus-sasl-debuginfo.
>
> (you can check this using gdb's 'info shared' command)
>
>> I've also run 'rebaseall' on the off chance that it would help - it
>> didn't!
>>
>> Still open to suggestions if anyone has any "light bulb" notions. :-)
>
Hi Jon. Thanks for the swift reply.

I've installed the debug as you suggested but it doesn't shed much light
to me. The attached gdb output doesn't seem any more enlightening. I'm a
little (!) out of my depth I think.

-- 
Sam Edge

SamEdge@thor ~
$ gdb svn
GNU gdb (GDB) (Cygwin 7.10.1-1) 7.10.1
Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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and "show warranty" for details.
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Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
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For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from svn...Reading symbols from /usr/lib/debug//usr/bin/svn.exe.dbg...done.
done.
(gdb) set cygwin-exceptions on
(gdb) run ls svn+ssh://cmserver.XXXXXXXXXX.com/edl/
Starting program: /usr/bin/svn ls svn+ssh://cmserver.XXXXXXXXXX.com/edl/
[New Thread 5372.0x9ec]
[New Thread 5372.0x16c0]
[New Thread 5372.0x1044]
[New Thread 5372.0x1208]

Program received signal SIGSEGV, Segmentation fault.
0x00000003e9f63780 in ?? ()
(gdb) info shared
From                To                  Syms Read   Shared Object Library
0x0000000076cb1000  0x0000000076e594e8  Yes (*)     /cygdrive/c/Windows/SYSTEM32/ntdll.dll
0x0000000076a91000  0x0000000076baeaf4  Yes (*)     /cygdrive/c/Windows/system32/kernel32.dll
0x000007fefcb11000  0x000007fefcb7913c  Yes (*)     /cygdrive/c/Windows/system32/KERNELBASE.dll
0x00000003ed3d1000  0x00000003ed437020  Yes         /usr/bin/cygsvn_client-1-0.dll
0x00000003ed2c1000  0x00000003ed2d301c  Yes         /usr/bin/cygsvn_ra-1-0.dll
0x00000003ed2b1000  0x00000003ed2bf020  Yes         /usr/bin/cygsvn_ra_local-1-0.dll
0x00000003ed221000  0x00000003ed257020  Yes         /usr/bin/cygsvn_repos-1-0.dll
0x00000003ed3b1000  0x00000003ed3c101c  Yes         /usr/bin/cygsvn_fs-1-0.dll
0x00000003ed381000  0x00000003ed3ad020  Yes         /usr/bin/cygsvn_fs_base-1-0.dll
0x00000003ed651000  0x00000003ed666020  Yes         /usr/bin/cygsvn_delta-1-0.dll
0x00000003ed121000  0x00000003ed21201c  Yes         /usr/bin/cygsvn_subr-1-0.dll
0x00000003fa761000  0x00000003fa78d018  Yes (*)     /usr/bin/cygapr-1-0.dll
0x0000000180041000  0x0000000180610000  Yes         /usr/bin/cygwin1.dll
0x00000003ece51000  0x00000003ece5c018  Yes (*)     /usr/bin/cyguuid-1.dll
0x00000003eeb21000  0x00000003eeb33018  Yes (*)     /usr/bin/cygintl-8.dll
0x00000003f4231000  0x00000003f4334018  Yes (*)     /usr/bin/cygiconv-2.dll
0x00000003f4bf1000  0x00000003f4c0901c  Yes (*)     /usr/bin/cyggcc_s-seh-1.dll
0x00000003fa731000  0x00000003fa75801c  Yes (*)     /usr/bin/cygaprutil-1-0.dll
0x00000003f53f1000  0x00000003f53fb018  Yes (*)     /usr/bin/cygcrypt-0.dll
0x00000003f4c81000  0x00000003f4cab018  Yes (*)     /usr/bin/cygexpat-1.dll
0x00000003ed6b1000  0x00000003ed7ab01c  Yes (*)     /usr/bin/cygsqlite3-0.dll
0x00000003ecca1000  0x00000003eccbc014  Yes (*)     /usr/bin/cygz.dll
---Type <return> to continue, or q <return> to quit---
0x000007fefcbc1000  0x000007fefcd2ce4c  Yes (*)     /cygdrive/c/Windows/system32/CRYPT32.dll
0x000007fefdf11000  0x000007fefdfae4bc  Yes (*)     /cygdrive/c/Windows/system32/msvcrt.dll
0x000007fefc9e1000  0x000007fefc9ee00c  Yes (*)     /cygdrive/c/Windows/system32/MSASN1.dll
0x00000003ed621000  0x00000003ed62b020  Yes         /usr/bin/cygsvn_fs_util-1-0.dll
0x00000003f4fa1000  0x00000003f5128018  Yes (*)     /usr/bin/cygdb-5.3.dll
0x00000003ed331000  0x00000003ed378020  Yes         /usr/bin/cygsvn_fs_fs-1-0.dll
0x00000003ed2e1000  0x00000003ed32a01c  Yes         /usr/bin/cygsvn_fs_x-1-0.dll
0x00000003ed281000  0x00000003ed2af020  Yes         /usr/bin/cygsvn_ra_serf-1-0.dll
0x00000003ed7e1000  0x00000003ed7fa1a0  Yes (*)     /usr/bin/cygserf-1-0.dll
0x00000003f51b1000  0x00000003f53e601c  Yes (*)     /usr/bin/cygcrypto-1.0.0.dll
0x00000003f44c1000  0x00000003f4506020  Yes (*)     /usr/bin/cyggssapi_krb5-2.dll
0x00000003ee7a1000  0x00000003ee7d401c  Yes (*)     /usr/bin/cygk5crypto-3.dll
0x00000003ee6d1000  0x00000003ee6df020  Yes (*)     /usr/bin/cygkrb5support-0.dll
0x00000003ee6e1000  0x00000003ee79b018  Yes (*)     /usr/bin/cygkrb5-3.dll
0x00000003f5401000  0x00000003f540c01c  Yes (*)     /usr/bin/cygcom_err-2.dll
0x00000003ed5a1000  0x00000003ed60901c  Yes (*)     /usr/bin/cygssl-1.0.0.dll
0x00000003ed261000  0x00000003ed27f020  Yes         /usr/bin/cygsvn_ra_svn-1-0.dll
0x00000003ed801000  0x00000003ed81f018  Yes         /usr/bin/cygsasl2-3.dll
0x00000003ed071000  0x00000003ed11901c  Yes         /usr/bin/cygsvn_wc-1-0.dll
0x00000003ed631000  0x00000003ed64a01c  Yes         /usr/bin/cygsvn_diff-1-0.dll
0x000007fefdfb1000  0x000007fefe08a624  Yes (*)     /cygdrive/c/Windows/system32/advapi32.dll
0x000007fefde41000  0x000007fefde5e39a  Yes (*)     /cygdrive/c/Windows/SYSTEM32/sechost.dll
0x000007fefd631000  0x000007fefd75c924  Yes (*)     /cygdrive/c/Windows/system32/RPCRT4.dll
0x000007fefa9b1000  0x000007fefa9c5034  Yes (*)     /cygdrive/c/Windows/system32/netapi32.dll
0x000007fefa9a1000  0x000007fefa9ab01c  Yes (*)     /cygdrive/c/Windows/system32/netutils.dll
0x000007fefc6f1000  0x000007fefc71265c  Yes (*)     /cygdrive/c/Windows/system32/srvcli.dll
0x000007fefa981000  0x000007fefa994388  Yes (*)     /cygdrive/c/Windows/system32/wkscli.dll
0x000007fefa961000  0x000007fefa973094  Yes (*)     /cygdrive/c/Windows/system32/SAMCLI.DLL
0x000007fefb291000  0x000007fefb2ac93c  Yes (*)     /cygdrive/c/Windows/system32/SAMLIB.dll
0x000007fefc3e1000  0x000007fefc40ec1c  Yes (*)     /cygdrive/c/Windows/system32/authz.dll
0x000007fef9241000  0x000007fef924b194  Yes (*)     /cygdrive/c/Windows/system32/dsrole.dll
0x00000003e9fe1000  0x00000003e9fed01c  Yes         /usr/lib/sasl2_3/cyganonymous-3.dll
0x00000003e9fd1000  0x00000003e9fdd01c  Yes         /usr/lib/sasl2_3/cygcrammd5-3.dll
(*): Shared library is missing debugging information.
(gdb) info threads
  Id   Target Id         Frame
  4    Thread 5372.0x1208 0x0000000076cfd63a in ntdll!ZwWaitForWorkViaWorkerFactory () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
  3    Thread 5372.0x1044 0x0000000076cfc2ea in ntdll!ZwWaitForMultipleObjects () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
  2    Thread 5372.0x16c0 0x0000000076cfbd9a in ntdll!ZwReadFile () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
* 1    Thread 5372.0x9ec 0x00000003e9f63780 in ?? ()
(gdb) list
3098                      err, _("When using svn+ssh:// URLs, keep in mind that the "
3099                             "--username and --password options are ignored "
3100                             "because authentication is performed by SSH, not "
3101                             "Subversion"));
3102            }
3103
3104          return err;
3105        }
3106
3107      return SVN_NO_ERROR;
--
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