[PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

Since we ony support the TTB1 quirk for AArch64 contexts, and
consequently only for 64-bit builds, the sign-extension aspect of the
"are all bits above IAS consistent?" check should implicitly only apply
to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
don't inadvertently get sign-extended, and thus considered invalid, if
they happen to be above 2GB in the TTB0 region.

Reported-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>

---

Logically there may also have been a UBSAN "shift greater than size of
type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
and that's now my only easy "spin up a 32-bit VM" option to hand :)

 drivers/iommu/io-pgtable-arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 983b08477e64..04fbd4bf0ff9 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c

@@ -468,7 +468,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte *ptep = data->pgd;
 	int ret, lvl = data->start_level;
 	arm_lpae_iopte prot;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = (s64)iova >> cfg->ias;
 
 	/* If no access, then nothing to do */
 	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))

@@ -645,7 +645,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
 	arm_lpae_iopte *ptep = data->pgd;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = (s64)iova >> cfg->ias;
 
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return 0;

-- 
2.23.0.dirty


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