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>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 46727ce9280dc7296feb7d130f362851d5799587..08c53c5a046f267502e26c5b7f918e88ee05dea7 100644 (file)
--- 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);