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iommu/iova: Make rcache limit_pfn handling more robust 

When popping a pfn from an rcache, we are currently checking it directly
against limit_pfn for viability. Since this represents iova->pfn_lo, it
is technically possible for the corresponding iova->pfn_hi to be greater
than limit_pfn. Although we generally get away with it in practice since
limit_pfn is typically a power-of-two boundary and the IOVAs are
size-aligned, it's pretty trivial to make the iova_rcache_get() path
take the allocation size into account for complete safety.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2017-09-19 14:48:40 +01:00 committed by Joerg Roedel
parent 7595dc588a
commit b826ee9a4f
1 changed files with 3 additions and 3 deletions
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6
drivers/iommu/iova.c
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@ -406,7 +406,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
unsigned long iova_pfn;
struct iova *new_iova;
iova_pfn = iova_rcache_get(iovad, size, limit_pfn);
iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1);
if (iova_pfn)
return iova_pfn;
@ -823,7 +823,7 @@ static unsigned long iova_magazine_pop(struct iova_magazine *mag,
{
BUG_ON(iova_magazine_empty(mag));
if (mag->pfns[mag->size - 1] >= limit_pfn)
if (mag->pfns[mag->size - 1] > limit_pfn)
return 0;
return mag->pfns[--mag->size];
@ -977,7 +977,7 @@ static unsigned long iova_rcache_get(struct iova_domain *iovad,
if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
return 0;
return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn);
return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size);
}
/*