Re: [Xen-devel] [PATCH] tools/libxc: Initialise parameters in map_p2m_list() for error paths

[Juergen Gross <jgross@xxxxxxxx>]

On 07/01/16 16:06, Ian Campbell wrote:
> On Thu, 2016-01-07 at 14:55 +0000, Andrew Cooper wrote:
>> c/s 7bf7458 "libxc: support of linear p2m list for migration of
>> pv-domains" breaks compilation on CentOS 7 because of 'ptes' being
>> possibly uninitialised after the 'err:' label.
>>
>> The migration will fail early for conditions which would cause the for()
>> loop not to run, but the compiler doesn't know this.
> 
> Isn't the issue the malloc goto err path before the loop? Looks like that
> should have the error behaviour from the earlier half of the function
> rather than the latter.

Yes to both. OTOH with Andrew's patch the code behaves correctly.

> There might also be a path if ctx->x86_pv.levels == 0, in which case the
> loop will never run, that's the sort of thing which could be checked (or
> even perhaps asserted) on entry to the function.

As there is no function vector involved between setting levels and
consuming it I doubt this makes really sense.


Juergen

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