[PATCH 5/6] ASoC: SOF: ipc3-control: Fix TOCTOU in bytes_put and bytes_get

[Peter Ujfalusi <peter.ujfalusi@linux.intel.com>]

In sof_ipc3_bytes_put(), the size used for the memcpy is derived from
the old data->size already in the buffer, not the incoming new data's
size field. If the new data has a different size, the copy length is
wrong: it may truncate valid data or copy stale bytes.

Similarly, sof_ipc3_bytes_get() checks data->size against max_size
without accounting for the sizeof(struct sof_ipc_ctrl_data) offset
of the flex array within the allocation.

Fix bytes_put to validate and use the incoming data's sof_abi_hdr.size
from ucontrol before copying. Fix bytes_get to subtract sizeof(*cdata)
from the bounds check to match the actual available space.

Fixes: 544ac8858f24 ("ASoC: SOF: Add bytes_get/put control IPC ops for IPC3")
Cc: stable@vger.kernel.org
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 sound/soc/sof/ipc3-control.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/sound/soc/sof/ipc3-control.c b/sound/soc/sof/ipc3-control.c
index 4b907d8cf58a..1f5538bbc50f 100644
--- a/sound/soc/sof/ipc3-control.c
+++ b/sound/soc/sof/ipc3-control.c
@@ -315,10 +315,13 @@ static int sof_ipc3_bytes_get(struct snd_sof_control *scontrol,
 	}
 
 	/* be->max has been verified to be >= sizeof(struct sof_abi_hdr) */
-	if (data->size > scontrol->max_size - sizeof(*data)) {
+	if (data->size > scontrol->max_size - sizeof(*cdata) -
+				    sizeof(*data)) {
 		dev_err_ratelimited(scomp->dev,
 				    "%u bytes of control data is invalid, max is %zu\n",
-				    data->size, scontrol->max_size - sizeof(*data));
+				    data->size,
+				    scontrol->max_size - sizeof(*cdata) -
+				    sizeof(*data));
 		return -EINVAL;
 	}
 
@@ -336,6 +339,8 @@ static int sof_ipc3_bytes_put(struct snd_sof_control *scontrol,
 	struct sof_ipc_ctrl_data *cdata = scontrol->ipc_control_data;
 	struct snd_soc_component *scomp = scontrol->scomp;
 	struct sof_abi_hdr *data = cdata->data;
+	const struct sof_abi_hdr *new_hdr =
+		(const struct sof_abi_hdr *)ucontrol->value.bytes.data;
 	size_t size;
 
 	if (scontrol->max_size > sizeof(ucontrol->value.bytes.data)) {
@@ -344,14 +349,18 @@ static int sof_ipc3_bytes_put(struct snd_sof_control *scontrol,
 		return -EINVAL;
 	}
 
-	/* scontrol->max_size has been verified to be >= sizeof(struct sof_abi_hdr) */
-	if (data->size > scontrol->max_size - sizeof(*data)) {
-		dev_err_ratelimited(scomp->dev, "data size too big %u bytes max is %zu\n",
-				    data->size, scontrol->max_size - sizeof(*data));
+	/* Validate the new data's size, not the old one */
+	if (new_hdr->size > scontrol->max_size - sizeof(*cdata) -
+				    sizeof(*new_hdr)) {
+		dev_err_ratelimited(scomp->dev,
+				    "data size too big %u bytes max is %zu\n",
+				    new_hdr->size,
+				    scontrol->max_size - sizeof(*cdata) -
+				    sizeof(*new_hdr));
 		return -EINVAL;
 	}
 
-	size = data->size + sizeof(*data);
+	size = new_hdr->size + sizeof(*new_hdr);
 
 	/* copy from kcontrol */
 	memcpy(data, ucontrol->value.bytes.data, size);
-- 
2.54.0