[PATCH] iio: proximity: aw96103: validate firmware data length

The firmware parser reads a length from the binary header and then uses
it to walk six-byte register/value entries. A truncated firmware image
can make the parser read beyond the copied firmware buffer. A value
smaller than the four-byte count field also underflows, producing a very
large length.

Read the little-endian field with get_unaligned_le32(), as previously
proposed by David Lechner. Validate the header size, reject an
underflowed length, ensure the resulting payload is contained in the
firmware image, and require it to contain whole register/value entries.

Fixes: 07b241262dca ("iio: proximity: aw96103: Add support for aw96103/aw96105 proximity sensor")
Link: https://lore.kernel.org/r/20260314-iio-proximity-aw96103-fix-firmware-read-v1-1-c74fe9ccd82b@baylibre.com
Cc: [email protected]
Signed-off-by: Laxman Acharya Padhya <[email protected]>
---
 drivers/iio/proximity/aw96103.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/proximity/aw96103.c b/drivers/iio/proximity/aw96103.c
index 8fbb755dc..8352d51e5 100644
--- a/drivers/iio/proximity/aw96103.c
+++ b/drivers/iio/proximity/aw96103.c
@@ -24,6 +24,7 @@
 #define AW96103_BIN_VALID_DATA_OFFSET		64
 #define AW96103_BIN_DATA_LEN_OFFSET		16
 #define AW96103_BIN_DATA_REG_NUM_SIZE		4
+#define AW96103_BIN_REG_SIZE			6
 #define AW96103_BIN_CHIP_TYPE_SIZE		8
 #define AW96103_BIN_CHIP_TYPE_OFFSET		24
 
@@ -229,14 +230,27 @@ static const struct aw_chip_info aw_chip_info_tbl[] = {
 	},
 };
 
-static void aw96103_parsing_bin_file(struct aw_bin *bin)
+static int aw96103_parsing_bin_file(struct aw_bin *bin)
 {
+	u32 data_len;
+
+	if (bin->len < AW96103_BIN_VALID_DATA_OFFSET)
+		return -EINVAL;
+
+	data_len = get_unaligned_le32(bin->data + AW96103_BIN_DATA_LEN_OFFSET);
+	if (data_len < AW96103_BIN_DATA_REG_NUM_SIZE)
+		return -EINVAL;
+
+	bin->valid_data_len = data_len - AW96103_BIN_DATA_REG_NUM_SIZE;
+	if (bin->valid_data_len > bin->len - AW96103_BIN_VALID_DATA_OFFSET ||
+	    bin->valid_data_len % AW96103_BIN_REG_SIZE)
+		return -EINVAL;
+
 	bin->valid_data_addr = AW96103_BIN_VALID_DATA_OFFSET;
-	bin->valid_data_len =
-		*(unsigned int *)(bin->data + AW96103_BIN_DATA_LEN_OFFSET) -
-		AW96103_BIN_DATA_REG_NUM_SIZE;
 	memcpy(bin->chip_type, bin->data + AW96103_BIN_CHIP_TYPE_OFFSET,
 	       AW96103_BIN_CHIP_TYPE_SIZE);
+
+	return 0;
 }
 
 static const struct regmap_config aw96103_regmap_confg = {
@@ -500,7 +514,7 @@ static int aw96103_bin_valid_loaded(struct aw96103 *aw96103,
 	int ret;
 
 	for (i = 0; i < aw_bin_data_s->valid_data_len;
-	     i += 6, start_addr += 6) {
+	     i += AW96103_BIN_REG_SIZE, start_addr += AW96103_BIN_REG_SIZE) {
 		reg_addr = get_unaligned_le16(aw_bin_data_s->data + start_addr);
 		reg_data = get_unaligned_le32(aw_bin_data_s->data +
 					      start_addr + 2);
@@ -550,6 +564,8 @@ static int aw96103_para_loaded(struct aw96103 *aw96103)
 static int aw96103_cfg_all_loaded(const struct firmware *cont,
 				  struct aw96103 *aw96103)
 {
+	int ret;
+
 	if (!cont)
 		return -EINVAL;
 
@@ -561,7 +577,9 @@ static int aw96103_cfg_all_loaded(const struct firmware *cont,
 	aw_bin->len = cont->size;
 	memcpy(aw_bin->data, cont->data, cont->size);
 	release_firmware(cont);
-	aw96103_parsing_bin_file(aw_bin);
+	ret = aw96103_parsing_bin_file(aw_bin);
+	if (ret)
+		return ret;
 
 	return aw96103_bin_valid_loaded(aw96103, aw_bin);
 }
-- 
2.51.2