firmware: cs_dsp: Validate payload length before processing block

JIRA: https://issues.redhat.com/browse/RHEL-53640
CVE: CVE-2024-42237

commit 6598afa
Author: Richard Fitzgerald <rf@opensource.cirrus.com>
Date:   Thu Jun 27 15:14:31 2024 +0100

    firmware: cs_dsp: Validate payload length before processing block

    Move the payload length check in cs_dsp_load() and cs_dsp_coeff_load()
    to be done before the block is processed.

    The check that the length of a block payload does not exceed the number
    of remaining bytes in the firwmware file buffer was being done near the
    end of the loop iteration. However, some code before that check used the
    length field without validating it.

    Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
    Fixes: f6bc909 ("firmware: cs_dsp: add driver to support firmware loading on Cirrus Logic DSPs")
    Link: https://patch.msgid.link/20240627141432.93056-4-rf@opensource.cirrus.com
    Signed-off-by: Mark Brown <broonie@kernel.org>

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

drivers/firmware/cirrus/cs_dsp.c

@@ -1529,6 +1529,12 @@ static int cs_dsp_load(struct cs_dsp *dsp, const struct firmware *firmware,
 	while (pos < firmware->size &&
 	       sizeof(*region) < firmware->size - pos) {
 		region = (void *)&(firmware->data[pos]);
+
+		if (le32_to_cpu(region->len) > firmware->size - pos - sizeof(*region)) {
+			ret = -EOVERFLOW;
+			goto out_fw;
+		}
+
 		region_name = "Unknown";
 		reg = 0;
 		text = NULL;
@@ -1585,16 +1591,6 @@ static int cs_dsp_load(struct cs_dsp *dsp, const struct firmware *firmware,
 			   regions, le32_to_cpu(region->len), offset,
 			   region_name);
 
-		if (le32_to_cpu(region->len) >
-		    firmware->size - pos - sizeof(*region)) {
-			cs_dsp_err(dsp,
-				   "%s.%d: %s region len %d bytes exceeds file length %zu\n",
-				   file, regions, region_name,
-				   le32_to_cpu(region->len), firmware->size);
-			ret = -EINVAL;
-			goto out_fw;
-		}
-
 		if (text) {
 			memcpy(text, region->data, le32_to_cpu(region->len));
 			cs_dsp_info(dsp, "%s: %s\n", file, text);
@@ -2219,6 +2215,11 @@ static int cs_dsp_load_coeff(struct cs_dsp *dsp, const struct firmware *firmware
 	       sizeof(*blk) < firmware->size - pos) {
 		blk = (void *)(&firmware->data[pos]);
 
+		if (le32_to_cpu(blk->len) > firmware->size - pos - sizeof(*blk)) {
+			ret = -EOVERFLOW;
+			goto out_fw;
+		}
+
 		type = le16_to_cpu(blk->type);
 		offset = le16_to_cpu(blk->offset);
 		version = le32_to_cpu(blk->ver) >> 8;
@@ -2315,17 +2316,6 @@ static int cs_dsp_load_coeff(struct cs_dsp *dsp, const struct firmware *firmware
 		}
 
 		if (reg) {
-			if (le32_to_cpu(blk->len) >
-			    firmware->size - pos - sizeof(*blk)) {
-				cs_dsp_err(dsp,
-					   "%s.%d: %s region len %d bytes exceeds file length %zu\n",
-					   file, blocks, region_name,
-					   le32_to_cpu(blk->len),
-					   firmware->size);
-				ret = -EINVAL;
-				goto out_fw;
-			}
-
 			buf = cs_dsp_buf_alloc(blk->data,
 					       le32_to_cpu(blk->len),
 					       &buf_list);
@@ -2365,6 +2355,10 @@ static int cs_dsp_load_coeff(struct cs_dsp *dsp, const struct firmware *firmware
 	regmap_async_complete(regmap);
 	cs_dsp_buf_free(&buf_list);
 	kfree(text);
+
+	if (ret == -EOVERFLOW)
+		cs_dsp_err(dsp, "%s: file content overflows file data\n", file);
+
 	return ret;
 }