iommu: Fix missing return check of arm_lpae_init_pte

UAF scenario may occur in clients with EL1 privileges for
iova mappings when we miss to check the return value of
arm_lpae_init_pte which may lead to an PTE be counted as
it was set even if it was already existing. This can cause a
dangling IOMMU PTE to be left mapped pointing to a
freed object and cause UAF in the client if the dangling PTE
is accessed after a failed unmap operation.

Fixes: 27de1978c331 ("ANDROID: GKI: iommu/io-pgtable-arm: LPAE related updates by vendor")
Change-Id: I674b9b520e705b8f8e63ba20ed76e64cb2fe0f47
Signed-off-by: Pratyush Brahma <quic_pbrahma@quicinc.com>

Author: Pratyush Brahma

drivers/iommu/io-pgtable-arm.c

@@ -597,9 +597,11 @@ static int arm_lpae_map_sg(struct io_pgtable_ops *ops, unsigned long iova,
 				arm_lpae_iopte *ptep = ms.pgtable +
 					ARM_LPAE_LVL_IDX(iova, MAP_STATE_LVL,
 							 data);
-				arm_lpae_init_pte(
+				ret = arm_lpae_init_pte(
 					data, iova, phys, prot, MAP_STATE_LVL,
 					ptep, ms.prev_pgtable, false);
+				if (ret)
+					goto out_err;
 				ms.num_pte++;
 			} else {
 				ret = __arm_lpae_map(data, iova, phys, pgsize,