Re: [libvirt] [PATCH for v4.6.0] cgroups: Don't leave stale pointers around after virCgroupFree
On Mon, Jul 30, 2018 at 09:48:51AM +0100, Daniel P. Berrangé wrote:
On Mon, Jul 30, 2018 at 10:25:05AM +0200, Michal Privoznik wrote:
> One of the attributes that original virCgroupFree() had was it
> set passed pointer to NULL. For instance in the following code
> the latter call would be practically a no-op:
>
> virCgroupFree(&var);
> virCgroupFree(&var);
>
> However, this behaviour of the function was changed in
> 0f80c71822d824 but corresponding 'var = NULL' lines were not
> added leading to double free:
Sigh, can we please just revert that change. It is going in completely the
oppposite of what we should be doing. We want to change more functions to
take a ptr to a ptr, precisely because it avoids this double-free problem.
Even more crazy, this change was done so that VIR_DEFINE_AUTOPTR_FUNC()
could be used to define a free function which takes a ptr to a ptr.
Both of these changes should be reverted, as the previously existing
virCgroupFree should be used as the attribute((cleanup)) function directly
with no wrapper created.
Regards,
Daniel
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