iommu/io-pgtable-arm: Avoid dereferencing bogus PTEs

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In the case of corrupted page tables, or when an invalid size is given,
__arm_lpae_unmap() may recurse beyond the maximum number of levels.
Unfortunately the detection of this error condition only happens *after*
calculating a nonsense offset from something which might not be a valid
table pointer and dereferencing that to see if it is a valid PTE.

Make things a little more robust by checking the level is valid before
doing anything which depends on it being so.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

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Robin Murphy 2015-12-04 17:52:58 +00:00 • committed by Will Deacon

parent a0d5c04c60

commit 2eb97c7861

1 changed files with 5 additions and 3 deletions

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drivers/iommu/io-pgtable-arm.c

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