[PATCH 2/4] firmware: cs_dsp: Return error if block header overflows file

[Richard Fitzgerald <rf@opensource.cirrus.com>]

Return an error from cs_dsp_power_up() if a block header is longer
than the amount of data left in the file.

The previous code in cs_dsp_load() and cs_dsp_load_coeff() would loop
while there was enough data left in the file for a valid region. This
protected against overrunning the end of the file data, but it didn't
abort the file processing with an error.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: f6bc909e7673 ("firmware: cs_dsp: add driver to support firmware loading on Cirrus Logic DSPs")
---
 drivers/firmware/cirrus/cs_dsp.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index 6eca62d31e20..47cf91be99a1 100644
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -1444,8 +1444,13 @@ static int cs_dsp_load(struct cs_dsp *dsp, const struct firmware *firmware,
 	cs_dsp_dbg(dsp, "%s: timestamp %llu\n", file,
 		   le64_to_cpu(footer->timestamp));
 
-	while (pos < firmware->size &&
-	       sizeof(*region) < firmware->size - pos) {
+	while (pos < firmware->size) {
+		/* Is there enough data for a complete block header? */
+		if (sizeof(*region) > firmware->size - pos) {
+			ret = -EOVERFLOW;
+			goto out_fw;
+		}
+
 		region = (void *)&(firmware->data[pos]);
 		region_name = "Unknown";
 		reg = 0;
@@ -2133,8 +2138,13 @@ static int cs_dsp_load_coeff(struct cs_dsp *dsp, const struct firmware *firmware
 	pos = le32_to_cpu(hdr->len);
 
 	blocks = 0;
-	while (pos < firmware->size &&
-	       sizeof(*blk) < firmware->size - pos) {
+	while (pos < firmware->size) {
+		/* Is there enough data for a complete block header? */
+		if (sizeof(*blk) > firmware->size - pos) {
+			ret = -EOVERFLOW;
+			goto out_fw;
+		}
+
 		blk = (void *)(&firmware->data[pos]);
 
 		type = le16_to_cpu(blk->type);
-- 
2.39.2