Messages in this thread | | | Date | Thu, 31 May 2018 11:44:15 +0200 | From | Joerg Roedel <> | Subject | Re: [patch] /drivers/iommu/amd_iommu.c: variable unmap_size could be uninitialized |
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Hi Yizhuo Zhai,
thanks for your patch, but I think there is a better way to fix that. Please see below.
On Wed, May 30, 2018 at 11:02:54PM -0700, Yizhuo Zhai wrote: > Variable "unmap_size" is supposed to be initialized in function fetch_pte. > However, it's uninitialized if fetch_pte returns NULL. And "unmap_size" is used > outside the return check. > > From 377ccb647d3c6c6747f20a242b035bafc775c3be Mon Sep 17 00:00:00 2001 > > Signed-off-by: From: "yzhai003@ucr.edu" <yzhai003@ucr.edu> > --- > drivers/iommu/amd_iommu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c > index 8fb8c73..774e057 100644 > --- a/drivers/iommu/amd_iommu.c > +++ b/drivers/iommu/amd_iommu.c > @@ -1500,7 +1500,7 @@ static unsigned long iommu_unmap_page(struct > protection_domain *dom, > unsigned long page_size) > { > unsigned long long unmapped; > - unsigned long unmap_size; > + unsigned long unmap_size = 0;
That is not sufficient because fetch_pte is called in a loop, and when it returns NULL then unmap_size keeps the value of the previous invocation.
So from looking at the code, it is better to set page_size=0 in fetch_pte at the very beginning, before the function can return NULL.
Thanks,
Joerg
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