[alsa-devel] [PATCH] ASoC: SOF: topology: Fix bytes control size checks

[Pierre-Louis Bossart]

From: Dragos Tarcatu <dragos_tarcatu at mentor.com>

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 at intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Signed-off-by: Dragos Tarcatu <dragos_tarcatu at mentor.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/soc/sof/topology.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/sound/soc/sof/topology.c b/sound/soc/sof/topology.c
index 17fe6a1d5f3e..6096731e89ce 100644
--- a/sound/soc/sof/topology.c
+++ b/sound/soc/sof/topology.c
@@ -1048,15 +1048,16 @@ 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)
-- 
2.20.1