1 files changed, 32 insertions, 23 deletions

diff --git a/drivers/firmware/google/vpd_decode.c b/drivers/firmware/google/vpd_decode.c
index 943acaa8aa76..6c7ab2ba85d2 100644
--- a/drivers/firmware/google/vpd_decode.c
+++ b/drivers/firmware/google/vpd_decode.c
@@ -19,8 +19,8 @@
 
 #include "vpd_decode.h"
 
-static int vpd_decode_len(const s32 max_len, const u8 *in,
-			  s32 *length, s32 *decoded_len)
+static int vpd_decode_len(const u32 max_len, const u8 *in,
+			  u32 *length, u32 *decoded_len)
 {
 	u8 more;
 	int i = 0;
@@ -40,18 +40,39 @@ static int vpd_decode_len(const s32 max_len, const u8 *in,
 	} while (more);
 
 	*decoded_len = i;
+	return VPD_OK;
+}
+
+static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
+			    u32 *_consumed, const u8 **entry, u32 *entry_len)
+{
+	u32 decoded_len;
+	u32 consumed = *_consumed;
+
+	if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
+			   entry_len, &decoded_len) != VPD_OK)
+		return VPD_FAIL;
+	if (max_len - consumed < decoded_len)
+		return VPD_FAIL;
+
+	consumed += decoded_len;
+	*entry = input_buf + consumed;
+
+	/* entry_len is untrusted data and must be checked again. */
+	if (max_len - consumed < *entry_len)
+		return VPD_FAIL;
 
+	consumed += *entry_len;
+	*_consumed = consumed;
 	return VPD_OK;
 }
 
-int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed,
+int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
 		      vpd_decode_callback callback, void *callback_arg)
 {
 	int type;
-	int res;
-	s32 key_len;
-	s32 value_len;
-	s32 decoded_len;
+	u32 key_len;
+	u32 value_len;
 	const u8 *key;
 	const u8 *value;
 
@@ -66,26 +87,14 @@ int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed,
 	case VPD_TYPE_STRING:
 		(*consumed)++;
 
-		/* key */
-		res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed],
-				     &key_len, &decoded_len);
-		if (res != VPD_OK || *consumed + decoded_len >= max_len)
+		if (vpd_decode_entry(max_len, input_buf, consumed, &key,
+				     &key_len) != VPD_OK)
 			return VPD_FAIL;
 
-		*consumed += decoded_len;
-		key = &input_buf[*consumed];
-		*consumed += key_len;
-
-		/* value */
-		res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed],
-				     &value_len, &decoded_len);
-		if (res != VPD_OK || *consumed + decoded_len > max_len)
+		if (vpd_decode_entry(max_len, input_buf, consumed, &value,
+				     &value_len) != VPD_OK)
 			return VPD_FAIL;
 
-		*consumed += decoded_len;
-		value = &input_buf[*consumed];
-		*consumed += value_len;
-
 		if (type == VPD_TYPE_STRING)
 			return callback(key, key_len, value, value_len,
 					callback_arg);