IB/mlx5: Limit query HCA clock

When PAGE_SIZE is larger than 4K, the user shouldn't be able to query
the HCA core clock. This counter is within 4KB boundary and the
user-space shall not read information that's after this boundary.

Fixes: b368d7cb8ceb7 ('IB/mlx5: Add hca_core_clock_offset to...')
Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/main.c

@@ -991,7 +991,14 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev,
 	if (field_avail(typeof(resp), cqe_version, udata->outlen))
 		resp.response_length += sizeof(resp.cqe_version);
 
-	if (field_avail(typeof(resp), hca_core_clock_offset, udata->outlen)) {
+	/*
+	 * We don't want to expose information from the PCI bar that is located
+	 * after 4096 bytes, so if the arch only supports larger pages, let's
+	 * 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 =