[mythtv] Crash in dvbdev/transform.c

[Jesper Sörensen]

Kenneth Aafløy wrote:

>>On 01/06/2004, at 3:39 AM, Jesper Sörensen wrote:
>>    
>>
>>>I'm having some odd problems with DVB in MythTV, mainly regarding
>>>channel switching (frontend freezes waiting for data & sometimes
>>>backend crashes). There are probably a couple of different issues
>>>involved but you've got to start somewhere...
>>>
>>>I got this backtrace from a crash earlier this evening. I thought I
>>>saved more of it but it seems I only got the top part. Let me know if
>>>it's not enough and I'll try to get another trace.
>>>
>>>IIRC, the lower part of the backtrace was full of calls to write_ipack
>>>so it seems there was some heavy recursion going on. Is this normal?
>>>Could it be stack overflow causing this?
>>>      
>>>
>
>No, I don't think it is. It's probably caused by bad data. There was a patch 
>applied a while back which improved the handling of total bitrate in the 
>resulting mpeg stream. I belive this patch is the culrpint.
>
>I've attached a patch-for-testing, which probably could solve the segv 
>emmediatly at hand, but who knows what will emerge later on right?:)
>  
>

Thanks Kenneth! The patch looks trivial enough so I think it should be 
pretty safe :)

If I recall correctly, the segfault is not that easy to reproduce but 
I'll let you know if it happens again.

I'm also testing parts of the dvb-nosignal patch you posted a while ago. 
It was a very big patch (100 k) and parts of it has rotted with regards 
to 0.15/cvs head. I extracted the DVB parts (dvbcam, dvbchannel.* & 
dvbci) and are using only those. Do you think that's a bad idea? Was it 
an all-or-nothing patch? Anyway, it seems to work so far... I'll let you 
know how it turns out after some more testing.

/Jesper