Re: subversion 1.9.3-1 segfault

[Jon Turney <jon.turney@dronecode.org.uk>]

On 19/02/2016 15:59, Greg Chicares wrote:
> On 2016-02-13 18:41, David Rothenberger wrote:
>> On 2/9/2016 9:39 AM, Greg Chicares wrote:
>>> 'svn' segfaulted on a routine command:
[...]
>>
>> I wasn't able to get any useful information out of the stack trace.
>> Running addr2line does not show any functions. I'm not sure if this is
>> because you don't have the subversion-debuginfo package installed. I
>> would suggest you install this in case it makes a difference and the
>> failure happens again.
>
> I've installed 'subversion-debuginfo' and rebooted. After working okay
> for a few days, 'svn' is now segfaulting again. A coworker who did a
> brand-new Cygwin installation on a new machine yesterday reports 'svn'
> failing for her too, also with a stackdump.
>
> Here's my failing command:
>
> /lmi/mirror/lmi[1]$svn update
>
> Updating '.':
>
> zsh: segmentation fault (core dumped)  svn update
>
>
> (The last line means that 'zsh' caught the segfault, not that zsh crashed.)
>
> Today's stackdump looks much the same to me as last week's:
>
> Exception: STATUS_ACCESS_VIOLATION at eip=00000000
> eax=200C6268 ebx=200A8E98 ecx=0022C39C edx=00000000 esi=00000000 edi=00000011
> ebp=200C0250 esp=0022C35C program=C:\cygwin-lmi\bin\svn.exe, pid 1164, thread main
> cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
> Stack trace:
> Frame     Function  Args
> 200C0250  00000000 (00000000, 00000000, 6C1D5580, 200A0F40)
> 200A8E98  00000000 (00000002, 200A8E98, 2009EE70, 200AAF78)
> 2009F688  00000000 (6C701180, 6C701160, 00000000, 2009FA28)
> 2009EE70  2009F6D8 (00000000, 20052794, 200AAFB0, 00000000)
> 20052790  200C8268 (2004D788, 200430F4, 00000000, 20052C08)
> 200430F0  2009EE70 (2003EF00, 20038D6C, 20054CB0, 00000000)
> 20038D68  20052790 (00000000, 00000000, 20038E88, 00000000)
> End of stack trace
>
> ...and I don't see any useful information from 'addr2line':
>
> $addr2line -e /usr/bin/svn 0x200c0250 0x2009ee70 0x2009f6d8
>
> ??:0
> ??:0
> ??:0

This isn't the right command to use, because addr2line (unlike gdb) 
doesn't follow .gnu_debuglink pointers, so you need to point it directly 
at the detached debug symbols from the svn-debuginfo package, i.e. 
'addr2line -e /usr/lib/debug/usr/bin/svn.exe.dbg 0x200c0250 0x2009ee70 
0x2009f6d8'

But I'm afraid this probably still doesn't tell you anything useful, 
because the exception isn't occurring in svn.exe, but somewhere else.

In fact, the addresses in the backtrace look like they are in the heap, 
so it doesn't look like the stackdump unwinder has managed to record 
much useful information.


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