From 71f0be5e11b773ed4b09d1cc46099cdafacbd56a Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Sun, 23 Jan 2011 19:55:41 +0100
Subject: [PATCH] add blobmsg validation function

---
 blob.h    |  2 +-
 blobmsg.c | 28 +++++++++++++++++++++-------
 blobmsg.h |  1 +
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/blob.h b/blob.h
index 401a355..c9364e9 100644
--- a/blob.h
+++ b/blob.h
@@ -141,7 +141,7 @@ blob_id(struct blob_attr *attr)
  * blob_len: returns the length of the attribute's payload
  */
 static inline unsigned int
-blob_len(struct blob_attr *attr)
+blob_len(const struct blob_attr *attr)
 {
 	return (be32_to_cpu(attr->id_len) & BLOB_ATTR_LEN_MASK) - sizeof(struct blob_attr);
 }
diff --git a/blobmsg.c b/blobmsg.c
index 25b72ae..cc6b2f3 100644
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -15,6 +15,26 @@
 
 #include "blobmsg.h"
 
+bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
+{
+	const struct blobmsg_hdr *hdr;
+
+	if (blob_len(attr) < sizeof(struct blobmsg_hdr))
+		return false;
+
+	hdr = (void *) attr->data;
+	if (!hdr->namelen && name)
+		return false;
+
+	if (hdr->namelen > blob_len(attr))
+		return false;
+
+	if (hdr->name[hdr->namelen] != 0)
+		return false;
+
+	return true;
+}
+
 int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
                   struct blob_attr **tb, void *data, int len)
 {
@@ -45,13 +65,7 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
 			if (hdr->namelen != pslen[i])
 				continue;
 
-			if (!hdr->namelen)
-				return -1;
-
-			if (sizeof(*attr) + blobmsg_hdrlen(hdr->namelen) > blob_pad_len(attr))
-				return -1;
-
-			if (hdr->name[hdr->namelen] != 0)
+			if (!blobmsg_check_attr(attr, true))
 				return -1;
 
 			if (tb[i])
diff --git a/blobmsg.h b/blobmsg.h
index b50cca9..3085d00 100644
--- a/blobmsg.h
+++ b/blobmsg.h
@@ -65,6 +65,7 @@ static inline int blobmsg_data_len(struct blob_attr *attr)
 	return blob_len(attr) - (end - start);
 }
 
+bool blobmsg_check_attr(const struct blob_attr *attr, bool name);
 int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
                   struct blob_attr **tb, void *data, int len);