iommu: Do more input validation in iommu_map_sg()

The IOMMU-API works on page boundarys, unlike the DMA-API
which can work with sub-page buffers. The sg->offset
field does not make sense on the IOMMU level, so force it to
be 0. Do some error-path consolidation while at it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 18 insertions, 11 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 46727ce9280d..08c53c5a046f 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1127,26 +1127,33 @@ EXPORT_SYMBOL_GPL(iommu_unmap);
 size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
                          struct scatterlist *sg, unsigned int nents, int prot)
 {
-        int ret;
+        struct scatterlist *s;
         size_t mapped = 0;
         unsigned int i;
-        struct scatterlist *s;
+        int ret;
 
         for_each_sg(sg, s, nents, i) {
                 phys_addr_t phys = page_to_phys(sg_page(s));
-                size_t page_len = s->offset + s->length;
 
-                ret = iommu_map(domain, iova + mapped, phys, page_len, prot);
-                if (ret) {
-                        /* undo mappings already done */
-                        iommu_unmap(domain, iova, mapped);
-                        mapped = 0;
-                        break;
-                }
-                mapped += page_len;
+                /* We are mapping on page boundarys, so offset must be 0 */
+                if (s->offset)
+                        goto out_err;
+
+                ret = iommu_map(domain, iova + mapped, phys, s->length, prot);
+                if (ret)
+                        goto out_err;
+
+                mapped += s->length;
         }
 
         return mapped;
+
+out_err:
+        /* undo mappings already done */
+        iommu_unmap(domain, iova, mapped);
+
+        return 0;
+
 }
 EXPORT_SYMBOL_GPL(default_iommu_map_sg);