[PATCH 4.9 29/60] IB/mlx5: Fix kernel to user leak prevention logic

Greg Kroah-Hartman
2017-06-19T15:29:25Z

From: Eli Cohen <eli@mellanox.com>

commit de8d6e02efbdb259c67832ccf027d7ace9b91d5d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/hw/mlx5/main.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1105,13 +1105,13 @@ static struct ib_ucontext *mlx5_ib_alloc
* 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);
}