From: Eli Cohen <eli@mellanox.com>
Date: Tue, 3 Jan 2017 21:55:19 +0000 (+0200)
Subject: IB/mlx5: Fix kernel to user leak prevention logic
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=de8d6e02efbdb259c67832ccf027d7ace9b91d5d;p=openwrt%2Fstaging%2Fblogic.git

IB/mlx5: Fix kernel to user leak prevention logic

The logic was broken as it failed to update the response length for
architectures with PAGE_SIZE larger than 4kB. As a result further
extension of the ucontext response struct would fail.

Fixes: d69e3bcf7976 ('IB/mlx5: Mmap the HCA's core clock register to user-space')
Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
---

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 86c61e73780e..852b5b7b4897 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1148,13 +1148,13 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev,
 	 * pretend we don't support reading the HCA's core clock. This is also
 	 * forced by mmap function.
 	 */
-	if (PAGE_SIZE <= 4096 &&
-	    field_avail(typeof(resp), hca_core_clock_offset, udata->outlen)) {
-		resp.comp_mask |=
-			MLX5_IB_ALLOC_UCONTEXT_RESP_MASK_CORE_CLOCK_OFFSET;
-		resp.hca_core_clock_offset =
-			offsetof(struct mlx5_init_seg, internal_timer_h) %
-			PAGE_SIZE;
+	if (field_avail(typeof(resp), hca_core_clock_offset, udata->outlen)) {
+		if (PAGE_SIZE <= 4096) {
+			resp.comp_mask |=
+				MLX5_IB_ALLOC_UCONTEXT_RESP_MASK_CORE_CLOCK_OFFSET;
+			resp.hca_core_clock_offset =
+				offsetof(struct mlx5_init_seg, internal_timer_h) % PAGE_SIZE;
+		}
 		resp.response_length += sizeof(resp.hca_core_clock_offset) +
 					sizeof(resp.reserved2);
 	}