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SubjectRe: [PATCH] Intel IOMMU: get_domain_for_dev() leaks a bit of mem if dmar_find_matched_drhd_unit() fails.

PING

Any chance we could merge the updated patch below?

/Jesper


On Thu, 10 Feb 2011, Jesper Juhl wrote:

> On Thu, 10 Feb 2011, Alex Williamson wrote:
>
> > On Sun, 2011-02-06 at 21:11 +0100, Jesper Juhl wrote:
> > > I believe that there's a small memory leak in
> > > drivers/pci/intel-iommu.c:get_domain_for_dev().
> > >
> > > If the call to alloc_domain() succeeds but the subsequent call to
> > > dmar_find_matched_drhd_unit() fails, then the current code will return
> > > NULL without calling domain_exit(domain) which will leak the memory that
> > > alloc_domain() allocated.
> > >
> > > The easy fix for that is to simply move the call to alloc_domain() below
> > > the call to dmar_find_matched_drhd_unit() since the latter does not depend
> > > on the former.
> > >
> > > I also made the change of moving the assignment to local variable 'iommu'
> > > below both calls since there is no point in doing that work if either of
> > > those those calls fail.
> > >
> > > I also changed the 'return NULL' in the dmar_find_matched_drhd_unit()
> > > failure case to a 'goto error' since I figured that if rechecking
> > > 'find_domain(pdev)' makes sense after a alloc_domain() failure then it
> > > would also make sense after a dmar_find_matched_drhd_unit() failure.
> >
> > I don't think this change buys us anything. The goto error here seems
> > to be a hope that another cpu may have beat us and succeeded at
> > something we failed. In the case of matching the pci device to a drhd,
> > this should be deterministic (unless maybe we're racing a hot added
> > drhd). The rest seems fine to me. Thanks,
> >
> > Alex
> >
>
> Ok. Updated patch below that leaves out the 'goto error' bit for
> dmar_find_matched_drhd_unit() failures.
>
>
>
> There is a small memory leak in
> drivers/pci/intel-iommu.c:get_domain_for_dev().
>
> If the call to alloc_domain() succeeds but the subsequent call to
> dmar_find_matched_drhd_unit() fails, then the current code will return
> NULL without calling domain_exit(domain) which will leak the memory that
> alloc_domain() allocated.
>
> The easy fix for that is to simply move the call to alloc_domain() below
> the call to dmar_find_matched_drhd_unit() since the latter does not depend
> on the former.
>
> Signed-off-by: Jesper Juhl <jj@chaosbits.net>
> ---
> intel-iommu.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
> index 4789f8e..3cfb021 100644
> --- a/drivers/pci/intel-iommu.c
> +++ b/drivers/pci/intel-iommu.c
> @@ -1820,10 +1820,6 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
> }
> }
>
> - domain = alloc_domain();
> - if (!domain)
> - goto error;
> -
> /* Allocate new domain for the device */
> drhd = dmar_find_matched_drhd_unit(pdev);
> if (!drhd) {
> @@ -1831,8 +1827,11 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
> pci_name(pdev));
> return NULL;
> }
> - iommu = drhd->iommu;
> + domain = alloc_domain();
> + if (!domain)
> + goto error;
>
> + iommu = drhd->iommu;
> ret = iommu_attach_domain(domain, iommu);
> if (ret) {
> domain_exit(domain);
>
>
>

--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.



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