IB/rxe: Fix mem_check_range integer overflow

Update the range check to avoid integer-overflow in edge case.
Resolves CVE 2016-8636.

Signed-off-by: Eyal Itkin <eyal.itkin@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index d0faca294006..86a6585b847d 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -59,9 +59,11 @@ int mem_check_range(struct rxe_mem *mem, u64 iova, size_t length)
 
         case RXE_MEM_TYPE_MR:
         case RXE_MEM_TYPE_FMR:
-                return ((iova < mem->iova) ||
-                        ((iova + length) > (mem->iova + mem->length))) ?
-                        -EFAULT : 0;
+                if (iova < mem->iova ||
+                    length > mem->length ||
+                    iova > mem->iova + mem->length - length)
+                        return -EFAULT;
+                return 0;
 
         default:
                 return -EFAULT;