ASoC: SOF: topology: Fix bytes control size checks

When using the example SOF amp widget topology, KASAN dumps this
when the AMP bytes kcontrol gets loaded:

[ 9.579548] BUG: KASAN: slab-out-of-bounds in
sof_control_load+0x8cc/0xac0 [snd_sof]
[ 9.588194] Write of size 40 at addr ffff8882314559dc by task
systemd-udevd/2411

Fix that by rejecting the topology if the bytes data size > max_size

Fixes: 311ce4fe7637d ("ASoC: SOF: Add support for loading topologies")
Reviewed-by: Jaska Uimonen <jaska.uimonen@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Dragos Tarcatu <dragos_tarcatu@mentor.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191106145816.9367-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/sound/soc/sof/topology.c b/sound/soc/sof/topology.c
index 0aabb3190ddc..4452594c2e17 100644
--- a/sound/soc/sof/topology.c
+++ b/sound/soc/sof/topology.c
@@ -543,15 +543,16 @@ static int sof_control_load_bytes(struct snd_soc_component *scomp,
         struct soc_bytes_ext *sbe = (struct soc_bytes_ext *)kc->private_value;
         int max_size = sbe->max;
 
-        if (le32_to_cpu(control->priv.size) > max_size) {
+        /* init the get/put bytes data */
+        scontrol->size = sizeof(struct sof_ipc_ctrl_data) +
+                le32_to_cpu(control->priv.size);
+
+        if (scontrol->size > max_size) {
                 dev_err(sdev->dev, "err: bytes data size %d exceeds max %d.\n",
-                        control->priv.size, max_size);
+                        scontrol->size, max_size);
                 return -EINVAL;
         }
 
-        /* init the get/put bytes data */
-        scontrol->size = sizeof(struct sof_ipc_ctrl_data) +
-                le32_to_cpu(control->priv.size);
         scontrol->control_data = kzalloc(max_size, GFP_KERNEL);
         cdata = scontrol->control_data;
         if (!scontrol->control_data)