Re: [Xen-devel] [TESTDAY] xl cpupool-create segfaults if given invalid configuration

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-08-30 at 17:49 +0100, Ian Jackson wrote:
> Ian Jackson writes ("Re: [Xen-devel] [TESTDAY] xl cpupool-create segfaults if 
> given invalid configuration"):
> > I don't think this is correct.  It may happen to work with this
> > version of bison but I don't think you're allowed to assign to $3.
> 
> I think this fixes it.

It works for me.
> 
> Ian.
> 
> From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Subject: [PATCH] libxl: fix double free on some config parser errors
> 
> If libxlu_cfg_y.y encountered a config file error, the code generated
> by bison would sometimes _both_ run the %destructor _and_ call
> xlu__cfg_set_store for the same XLU_ConfigSetting* semantic value.
> The result would be a double free.
> 
> This appears to be because of the use of a mid-rule action.  There is
> some discussion of the problems with destructors and mid-rule action
> error handling in "(bison)Mid-Rule Actions".  This area is complex and
> best avoided.
> 
> So fix the bug by abolishing the use of a mid-rule action, which was
> in any case not necessary here.
> 
> Also while we are there rename the nonterminal rule "setting" to
> "assignment", to avoid confusion with the token type "setting", which
> had an identically name in a different namespace.  This was especially
> confusing because the nonterminal "setting" did not have "setting" as
> the type of its semantic value!  (In fact the nonterminal, now called
> "assignment", does not have a value so it does not have a value type.)
> 
> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

I shall apply in a moment, thanks.



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