Re: free(): double free detected in tcache 2

Denis Corbin <[email protected]> Thu, 27 Feb 2020 13:01:05 +0100

Newsgroups	gmane.comp.sysutils.backup.dar.support
Message-ID	<[email protected]>

On 26/02/2020 22:05, Graham Cobb wrote:
[...]
>>
>> How did you upgrade from 2.6.6 to 2.6.8?
>> - was it through distro package upgrade?
>> - did you grab the source code and compiled dar yourself?
>>
>> both way are valid, the impact are different on libraries dar relies on:
>> - in the first case you may have also upgraded some libraries
>> - in the second case you have not
> 
> Debian package upgrade. And, yes, it did install a new version of
> libgcc-s1 (10-20200211-1), which could either have a bug or be exposing
> a previously unknown dar bug. There is a newer version of libgcc-s1 in
> testing today so I will install that one for tonight's run. There is no
> Debian bug report for this, however.

that's exactly what I suspect,

> 
[...]
> 
> I will see if I get anything tonight.

OK thanks,

> 
>> By the way have you tried the workaround I suggested for the testing
>> phase (not using --sequential-read and relying on an isolated catalog)?
> 
> No. I don't have isolated catalogs and generating one on-the-fly would
> presumably take about as much time as doing the extra slice reads so I
> don't plan to bother. But thanks for the suggestion.

Absolutely not! At the end of archive creation dar/libdar writes the
catalogue into the generated archive, then adds some ending data and the
archive is completed.

The on-fly isolation let dar reuse this same in-memory data --- the
catalogue --- to drop it a second time into a new archive flagging this
archive as "isolated", thus just to be used as backup of a the catalogue
in the real archive, or as reference for furhter differential or
incremental backup, or yet for archive listing, or to feed dar_manager
with instead of using the real archive.

You can create an isolated catalogue afterward (-C option) this should
most of the time only require the last slice of the original archive

> 
> Graham
> 
> 
> 


Cheers,
Denis

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