RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()

Several corner cases, especially important on 32 bits:

- umem->iova is u64, the function argument should pass in u64 or
  iova will be truncated
- Check that the length is not too large for the iova
- Check that lengths > 4G don't overflow the GENMASK

Link: https://patch.msgid.link/r/2-v1-88303e9e509f+f7-ib_umem_types_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

2 files changed, 14 insertions, 8 deletions

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index e424a9de66c1..fd8f3888da52 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -84,14 +84,17 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
  */
 unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 				     unsigned long pgsz_bitmap,
-				     unsigned long virt)
+				     u64 virt)
 {
 	unsigned long curr_len = 0;
 	dma_addr_t curr_base = ~0;
-	unsigned long va, pgoff;
+	unsigned long pgoff;
 	struct scatterlist *sg;
-	dma_addr_t mask;
+	unsigned long mask = 0;
+	unsigned int bits;
 	dma_addr_t end;
+	u64 last_va;
+	u64 va;
 	int i;
 
 	umem->iova = va = virt;
@@ -109,9 +112,12 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 	 * number of required pages. Compute the largest page size that could
 	 * work based on VA address bits that don't change.
 	 */
-	mask = pgsz_bitmap &
-	       GENMASK(BITS_PER_LONG - 1,
-		       bits_per((umem->length - 1 + virt) ^ virt));
+	if (check_add_overflow(umem->length - 1, virt, &last_va))
+		return 0;
+	bits = bits_per(virt ^ last_va);
+	if (bits < BITS_PER_LONG)
+		mask = pgsz_bitmap & GENMASK(BITS_PER_LONG - 1, bits);
+
 	/* offset into first SGL */
 	pgoff = umem->address & ~PAGE_MASK;
 
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index bc1e6ed73b3f..4c8f433ba246 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -109,7 +109,7 @@ int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
 		      size_t length);
 unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 				     unsigned long pgsz_bitmap,
-				     unsigned long virt);
+				     u64 virt);
 
 /**
  * ib_umem_find_best_pgoff - Find best HW page size
@@ -234,7 +234,7 @@ static inline int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offs
 }
 static inline unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
 						   unsigned long pgsz_bitmap,
-						   unsigned long virt)
+						   u64 virt)
 {
 	return 0;
 }