Re: [LAU] repeatable jack related segfaults

On Thu, Oct 14, 2010 at 11:47:08PM +0200, Mathis Ahrens wrote:
> Julien Claassen wrote [2010-09-06] :
> >Hello everyone!
> > I'm experiencing trouble with jack and multiple servers. The
> >moment I start a second jackserver (for net I/O) and try:
> >jack_lsp -s new_name
> > jack_lsp segfaults.
>
> [follow-up: jack-devel]
>
> Hi!
>
> I have been bitten too, and found the bug:
>
> jack_get_ports() may return NULL if no ports matched,
> and jack_lsp uses this function on line 138 like this:
>
> ports = jack_get_ports( client, NULL, NULL, 0)
>
> for (i = 0; ports[i]; ++i) {
> ...
> }
>
> which obviously does not check for NULL.

this should be fixed.
but i would prefer this:
http://hochstrom.endofinternet.org/cgit/jack.git/commit/?id=0696759597e3c6d157e88a5738fe125185dd2dce

jack_lsp isnt calling jack_free() ... this is also pretty bad.

http://hochstrom.endofinternet.org/cgit/jack.git/commit/?id=6c7f82f06322516cbb4e13682c4e8e00a271dff7

>
> Attached is a patch that fixes this.
> Note that this also touches libjack/clients.c because
> I think it is wrong to return NULL when no ports match.

this should be discussed.

> There should be a distinction between a failed malloc and
> no matching ports.
> The array is already allocated, and the user has to free it
> anyway, so there is nothing wrong with returning it empty.

probably right.
i am a bit concerned that it might cause some subtle bugs, though.

>
> Patch is against SVN but should apply with offsets against
> 0.118, too.
>
> Bug test case:
> console1> jackd -dnet
> console2> jack_lsp
> Segmentation Fault
>
> Cheers,
> Mathis
>

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-- 
torben Hohn
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