Segfault in svnserve on UB 16.04 LTS sometimes

Hi all,

today I recognized a segfault in svnserver which seems to have been
documented for UB 16.04 LTS already:

> Apr 12 09:58:55 [...] kernel: [214930.125762] svnserve[556]: segfault at 7f5f75994f00 ip 00007f5f74ea1065 sp 00007ffddc1353f0 error 4 in libsvn_subr-1.so.1.0.0[7f5f74e43000+d3000]
> Apr 12 10:11:41 [...] kernel: [215695.854475] svnserve[3769]: segfault at 7f5f75994f00 ip 00007f5f74ea1065 sp 00007ffddc1353f0 error 4 in libsvn_subr-1.so.1.0.0[7f5f74e43000+d3000]

https://answers.launchpad.net/ubuntu/+question/404322

In all cases the version seems to be the default one distirbuted by
UB, 1.9.3, and one additional thing in common seems to be the usage
of hooks at least in some repos. The thread starter e.g. sends mails,
while in one of my repos I'm distributing commits using svnsync.

The problem is that it seems a bit difficult to reproduce what
triggers the problem: After recognizing it, I committed in some test
repo without any hook and in the repo with the hook and in both cases
wasn't able to trigger the segfault. Notice that I dind't restart
svnserve or the whole system before the tests, just as is. Looking at
the past logs, the problem somtimes happens every few minutes,
somtimes a few times a day and sometimes even not at all.

The interesting thing in my case is that I have some repo to which
things get committed multiple times a day automatically. That's as
well the repo with the hook. So there shouldn't be any day without any
commit to at least one repo, but I still have days without the problem.

If the segfaults happen, it seems to be exactly the same error
message until the main process gets restarted. My logs contained only
one exception from the rule: 7f5f75994640

> Apr 9 12:50:14 [...] kernel: [1677281.956916] svnserve[30221]: segfault at 7f0258833640 ip 00007f0257d40065 sp 00007ffe29fd1de0 error 4 in libsvn_subr-1.so.1.0.0[7f0257ce2000+d3000]
> Apr 9 12:55:09 [...] kernel: [1677577.574064] svnserve[31221]: segfault at 7f0258833640 ip 00007f0257d40065 sp 00007ffe29fd1de0 error 4 in libsvn_subr-1.so.1.0.0[7f0257ce2000+d3000]
[...]
> Apr 10 09:04:14 [...] kernel: [38850.248311] svnserve[19575]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 10 09:06:11 [...] kernel: [38967.469929] svnserve[19596]: segfault at 7f5f75994640 ip 00007f5f74ea1065 sp 00007ffddc1353f0 error 4 in libsvn_subr-1.so.1.0.0[7f5f74e43000+d3000]
> Apr 10 09:13:25 [...] kernel: [39401.078386] svnserve[20429]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 10 09:15:44 [...] kernel: [39539.710149] svnserve[21583]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
[...]
> Apr 11 12:07:13 [...] kernel: [136227.892728] svnserve[10466]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:08:38 [...] kernel: [136313.617840] svnserve[10515]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:08:38 [...] kernel: [136313.619646] svnserve[10512]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:09:41 [...] kernel: [136376.041439] svnserve[10591]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:10:10 [...] kernel: [136404.999582] svnserve[10629]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:11:25 [...] kernel: [136480.403404] svnserve[11437]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:11:25 [...] kernel: [136480.414366] svnserve[11438]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
> Apr 11 12:12:05 [...] kernel: [136520.407709] svnserve[11470]: segfault at 7fe569bcbc30 ip 00007fe5690d7065 sp 00007ffd951fdad0 error 4 in libsvn_subr-1.so.1.0.0[7fe569079000+d3000]
[...]
> Apr 12 09:58:55 [...] kernel: [214930.125762] svnserve[556]: segfault at 7f5f75994f00 ip 00007f5f74ea1065 sp 00007ffddc1353f0 error 4 in libsvn_subr-1.so.1.0.0[7f5f74e43000+d3000]
> Apr 12 10:11:41 [...] kernel: [215695.854475] svnserve[3769]: segfault at 7f5f75994f00 ip 00007f5f74ea1065 sp 00007ffddc1353f0 error 4 in libsvn_subr-1.so.1.0.0[7f5f74e43000+d3000]

Does the error tell anyone of you anything already? What should I do
to get some hints about which repo is affected with which operation?

The problem might not be related to commits at all, but read-only
access, as I have svnsync running for all repos etc.

Thanks for your suggestions!

Mit freundlichen Grüßen,

Thorsten Schöning

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